Enter Dropbox: The best free application ever with many many uses! Whenever I get any device (computer, phone, iPod) one of the first programs I install is Dropbox, which can view PDFs.
So I knew from prior experience that there is an editable 'Send PDF to...' dropdown in any print dialog. So I just created a PDFs folder in my Dropbox (you can just use the root of your dropbox if you want) and then just choose Print in any program and then click PDF - Edit Menu. Then hit the + button and select the folder you want to send your PDFs to and hit OK. The new menu entry will be the name of your folder, but if you go to the ~/Library/PDF Services folder you can rename the entry to whatever you want.
Now to virtually print something that you can view on any of your devices, just go to Print » PDF » [Your Dropbox Folder]. This has the advantage of one Print action creating something that can be viewed on multiple devices, with the caveat that your device must have an Internet connection the first time you view the document, since your mobile device(s) won't automatically sync with Dropbox like your Mac will (if you don't think you will have a connection when you need it, then just view the PDF on your device and it will download and be readily available later.)
[crarko adds: I use Dropbox like this all the time; I searched and was a bit surprised this hadn't been mentioned before. So here it is.]

