Be aware that if you leave an email message displayed/open on your iPhone, that message may not appear in Mail's messages list on your computer(s).
I've tried to replicate the issue with other messages, but wasn't able to do so 100% of the time. So I'm not sure why sometimes this is the case, and other times not. In any event, this is how it happened:
My iPhone was in Sleep mode.
On my MBP, I read an email message, flagged it, marked it Unread, and moved on to other email messages.
When finished (leaving Mail open), I put my MBP to sleep.
Later that evening on my iPhone, I opened that email message.
Without closing the message, I put my iPhone to sleep.
The next day, back in Mail on my MBP, that message was no longer in the messages list.
On my iPhone, the "missing" message was still displayed in the Mail app. I closed the message by returning to the messages list, and after a couple minutes, that message was once again in the messages list.
I'm using a MobileMe account, and in Account Settings » Advanced, I have Keep copies of messages for offline viewing set to All messages, but omit attachments.
So if you seem to be missing a message in Mail, check to make sure that message isn't displayed on your iPhone. If you can explain why sometimes this happens, but not always, that would be helpful, too!
You can use your iPhone to check if a household remote control is working. Start the Camera application, then point the remote in question toward the camera. Be sure the end of the remote with the dark plastic filter is facing the back of the iPhone. If the remote's batteries work, and the remote are functional, you will see a light glow in the picture of the remote in the iPhone's viewfinder window.
This can help narrow down a balky remote as to being broken or just having bad batteries.
This trick isn't unique to iPhones, but takes advantage of the camera's sensitivity to infrared light, and the fact that you never go anywhere without your iPhone!
I have several (more than 30) applications installed in my iPhone 2.0 (some of them are over 10MB). I've been a bit disappointed with the oh-so-slow syncs in iTunes due to the required backup process. Searching a bit, I found that I could disable the backups by setting a hidden iTunes preference. Quit iTunes, open Terminal, and enter this command:
Whe you next sync, your iPhone won't be backed up, so the actual sync will go quickly. If you feel the need to back up your data again at some point, simply change YES to NO and sync your device (quit iTunes before changing the setting). After the backup is done, you can then disable backups again. If you want to restore a previous backup, you must set this value to NO before trying the restore.
[robg adds: The long backup times with iPhone 2.0 software are a real pain -- while sometimes they seem speedy, my current "record" is 4.5 hours to back up about 500MB of data! (I wrote about long backup times in a recent piece for Macworld.) However, these backups are also important, as they store all of your application-specific data. So if you've added notes to a note-taking app, or made it through 20 levels of your favorite game, that data is part of what's being backed up. Without a backup, if you have to restore your iPhone, you'll lose all such data.
The other problem is that if you ever cancel a backup (by clicking the 'x' next to the progress bar), it apparently corrupts the existing backup -- so if you do then go to restore your iPhone, the backup won't be usable -- I've experienced this twice already myself. Because of this, a reasonable strategy would be to let one good backup run, then use this command to disable backups, use your phone as usual for a day (or whatever period of time you're comfortable with), re-enable backups, and then make sure the full backup is allowed to run, and repeat the process. Hopefully Apple can fix the abysmally slow backup speed in a future iPhone and/or iTunes update, so that such workarounds aren't needed. The recently-release iTunes 7.7.1 update may have improved things, but I need to do more testing before I can confirm that.]
To use the script, drop a PDF (or multiple PDFs) onto this application, and an internet location file/s will be created in the same folder. Drag these internet location files into Safari's Bookmarks window. Now sync your iPhone/Touch (make sure you have it set to sync Safari bookmarks) and open one of these bookmarks.
You can now view your PDF, even in landscape mode. I cobbled this script together with some help from posts at MacScripter.
[robg adds: This is a home-built alternative to the method used in this prior hint. I haven't tested this one.]
One of the more annoying things about the iPhone is the process of rearranging application icons. When all you could add to your phone's screen were a few web shortcuts, things weren't so bad. But now that you may have 50 or more third-party programs on your iPhone, it can be a real pain to drag newly-installed programs to the proper position on the proper screen. (How about a Mac program to ease the process, Apple?)
This is especially true if each of your screens are completely filled with the maximum of 16 icons, as something will have to shuffle off to another page while you're dragging -- and if you drop the new program onto a full screen, you'll then need to go find the application that got shuffled away, and move that one to its desired location, too.
To avoid this, just leave an empty spot on each screen, placing only 15 icons per screen. This solves the drag-arrange issue noted above. As you drag from screen to screen, no icons will jump off the page, as there's room to fit the one you're dragging around. The other advantage to leaving an empty spot is that -- assuming you only install one program at a time -- newly installed programs will always appear in the final position on the iPhone's main screen. This insures that none of my carefully-arranged pages are messed up by a new app install. I can also easily find the newest addition to my iPhone, and then drag it to the desired screen.
This is a simple tip, but I've found it makes the (still not pleasant) task of placing newly-installed app icons much easier. Of course, it also means you'll need more screens to manage your applications, as you're giving up one icon spot per page. For me, though (at least until I get closer to the 148 program limit), that's a minor inconvenience.
Something that may be fairly overlooked, but useful is using the iPhone Remote Application when you don't have access to a wireless network. I love taking my Macbook Pro on the go and have fallen in love with the Remote App, but there's not always a wireless network availiable! A quick and simple fix for this is to create your own secure wireless network using your Mac.
A step by step process would look something like this:
Click on the wireless icon in the menu bar and select Create Network.
Choose a name. If you are around other locked or untrusted wireless signals, you will want to choose an unused channel. (I would say use the two channel rule, but you're not transferring data here.) Make sure you put a password on it!
Open up the Network System Preferences panel. You'll want to create a new location to make it easier for future use, and it's easiest to stick with the default network settings. This step is optional, but if you're on the go, it makes it easy.
Go into the Security System Preferences pane, and make sure your firewall will allow access to iTunes. (Basically anything other than "Allow only essential services.") I have mine set to specific services, and allow incoming connections to iTunes.
Join the wireless network you created with your Mac, and you'll get a self-assigned IP address.
Join the network with your iPhone, and you're ready to rock n' roll -- remotely using your iPhone!
Your Mac is now a wireless router for your own mobile LAN. It's cool to use this in conjunction with Front Row (see this previous hint). If you have a Keynote presentation to give, you can export it as a QuickTime movie to iTunes and play/pause it using your iPhone, which seems to impress people. No matter where you go, you can use the Remote app now!
Turn on Settings » Airplane Mode.
Launch Safari and tap OK on dismiss the "Turn off Airplane Mode" dialog.
Enter your the bookmarklet in the location bar.
Dismiss the "Safari can't open the page" dialog.
Bookmark the page.
Turn off Airplane mode.
This works for bookmarklets that set the location property, and perhaps others as well. When Safari aborts the script because it can't open the page, it leaves the bookmarklet in the address field, allowing it to be bookmarked.
Using Mail on OS X, you can assign multiple sender addresses to one account. As covered in this ancient hint, this is done by just separating each address with a comma in the account's setup screen.
This same trick now works with the iPhone 2.0 firmware -- before it would just use the first address in the list. So if you have, for example, a Gmail account where you forward all your other mail addresses, you can now easily send mail from all of those addresses. Of course, your SMTP server must allow sending from foreign addresses for this to work.
Something that maybe not everyone has thought about with the iPhone is that the microphone is good enough to use in conjunction with an FM transmitter in the car as a speaker phone. This is a cheap and secure way to drive and speak at the same time.
The quality of the sound for the receiving part may not be the best, but it's good enough and it's better than using a headset. It even stops the music when the phone rings, such as a good installation of a phone kit for a car will do when receiving a call.
The iPhone app store is great, but some of the apps are poorly designed. One such design flaw can be seen in certain games that have music, but no volume control. This can often be fixed with the physical volume control on the iPhone, but what if you have an iPod touch, and the in-game music is too loud for your tastes?
It turns out that the new volume limit feature is a global setting, not just applicable to iPod music playback Go to Settings » Music » Volume Limit from the home screen, and set it to an agreeable level. This will automatically lower the volume of those pesky games.
You have to set it back when you're done, if you want to have your iPod music louder, of course.