I discovered that it is possible to type email, text messages, and enter text in most western languages. Simply tap and hold the button for the letter that most closely resembles the one you'd like to type. While holding the key down, an additional menu will appear where you can select the desired letter or accent.
For instance, to get an é, simply tap and hold E and select desired letter with accent from pop-up menu.
[robg adds: This feature was added with the iPhone 1.1.1 update, but as of now, it's not yet documented in the iPhone's user manual (which hasn't been updated for 1.1.1), nor anywhere that I can find on the iPhone support pages or even in the what's new video.]
Having used the iPhone for some testing, I saw that some SMSes corrupted the database file and the SMS app no longer worked. It would simply quit when I tried to open the SMS. The Apple suggested way to fix this problem would be to reset the iPhone by using the Settings » General » Reset » Erase all Content and Settings. But this would mean that you would have to resync your iPhone again. The easiest way I have found to do this is as follows.
Download any Terminal app from within the AppTap installer on the iPhone.
Open the terminal app and enter these commands:
$ rm Library/SMS/*
Note that you will lose all your saved SMS messages.
Exit the terminal app.
Restart your iPhone.
Your SMS app should now be as good as new while all your other data is intact.
[robg adds a very important note: This solution will possibly (a) void your warranty, (b) break the EULA, and (c) may have negative consequences with future Apple updates. If you've going to take this route, however, you could actually just use iNdependence to jailbreak the phone, and install dropbear (an SSH clone) at the same time (within iNdependence). Once that's done, you could use ssh (or sftp via Transmit, etc.) to connect to the phone and remove the bad file. Please consider the possible consequences above, however, before trying this solution -- anything that happens to your iPhone would be your responsibility, not anyone else's. Apple's Restor function is by far the safest, if most time consuming, solution.]
If you're on another Mac and want to sync a song/video to your iPhone, iTunes will clear your Music/Video Library. But the iPhone syncs Podcasts separately from the Music/Video Library, which means you can use Atomic Parsley to rewrite some flags on your songs/videos, and iTunes will sync the song/video as Podcasts without touching your Music/Video Library.
So, grab Atomic Parsley, and run it with these modifiers (URL and GUID can't be blank):
Now drag your song/video over to iTunes, and it'll show up as a Podcast and sync without touching your Library. Friendly note: The Podcast will show up by Artist metadata or podcastURL. This hint inspired by the methods covered in this one.
After an ill-advised (the site is somewhat dysfunctional even in desktop Safari) visit to a local book seller's web site on my iPhone crashed Safari, I found that I could no longer use Safari. Every time I opened it, it would be unresponsive for a few seconds, then crash, taking me back to the iPhone's home screen. Since Safari attempts to re-load the last visited site, it would attempt to reload the book seller's site upon launch and just crash again. Catch-22.
So I opened Mail, went to a message with a URL in the body and clicked that. That caused Safari to launch and open the URL passed by Mail. Problem solved!
I've been frustrated by the way we change the volume on the iPhone. The side button makes too large of a change, for my taste, with a single tap. But when I try to use the on-screen slider, I find I also have a hard time because my finger covers up the slider knob, so I can't see when I try to make small changes. I've discovered a way around this.
If you put your finger on the slider knob and start to move it, you can then move your finger (keep it in contact with the screen) quite far away -- I move my finger up into the main screen area -- and the slider will still move. Now I can make the small changes I want and watch the slider knob move without my finger blocking my view.
I'm often frustrated by the fact that the ".com" key exists for entering URLs, but not when entering an email address in a form on web pages.
Now instead of pressing the ".?123" key to get the period (.), I just hit the space bar twice followed by the delete key, then type com. I know it's the same number of taps, but this technique is certainly faster. Note that this will only work on iPhones that have been upgraded to version 1.1.1.
The headset that comes with iPhone allows you to use squeeze (click) once to pause, and double-squeeze to skip a song. But if you squeeze one time (while a song is playing), the iPhone's playback will pause, and if you then double-squeeze, the iPhone will skip back to the beginning of the album or playlist (depending on what you started playing).
Thus it is possible to skip back to the beginning without pulling the iPhone out of your pocket.
I'm not sure if this existed in older firmware, but in 1.1.1 when you're looking to type a new URL into Safari or Google Maps where the old URL is showing with the X button at the far right, you don't have to hit the X. All you have to do is start typing and the text field will automatically clear for the new text.
Nothing huge, but it'll save a second or two, right?
[robg adds: I can confirm that this works on the 1.0.2 iPhones as well.]
I found a solution to charging my iPhone while my Mac Mini is sleeping overnight. I didn't want to leave my computer on all night just to charge my iPhone, and didn't want to switch between the computer and wall charger every day. Usually, when you put your Mac to sleep, it cuts power to the USB ports, so your iPhone won't charge. To solve this, I ordered the "iPod Dock Connector to Firewire and USB 2.0" from the Apple store. With this cable, you can use the USB end to sync with your computer, and use the Firewire end to charge the phone overnight. Both ends stay connected to their respective ports all the time. This works because the Firewire ports still provide power when your Mac is sleeping, unlike USB. I currently have it plugged into a powered Firewire hub, but I've also tested it with a Apple 23" display and MacBook Pro.
[kirkmc adds: I can't test this, not having an iPhone here in France, but it makes sense that just plugging the phone into a powered hub will charge it; does it charge as well from a powered USB hub? Can anyone confirm?]
This is more of a GSM hint and common knowledge for GSM users, but relevant for iPhone users of this site who may have switched from CDMA carriers. Using standard GSM codes, you can change the numbers for conditional forwarding, such as forward if no answer, forward if busy, forward if out of reach. The default is to forward to voicemail, but there are times when you might want to change that. For instance, to forward calls to your home phone if you don't answer, dial this number (then tap the Call button)...
...where 1234567890 is your 10-digit home phone number. Dial ##61# and tap Call again to cancel that setting. When you do cancel, AT&T inserts the proper voicemail number, so everything will be as it was before you started. I do not know how it affects your minutes or if AT&T charges more for forwarded calls. Here's a complete list of conditional forwarding commands.