By default, Apple's iOS limits you to one e-mail signature. That's fine if you only need one, but I know plenty of business people who'd prefer different signatures for different e-mail accounts, different recipients (co-workers versus clients, for example), and so on.
Thanks to iOS 5's new Shortcuts feature, you can work around the one-signature limitation. Shortcuts, of course, are abbreviations that automatically expand into longer text blurbs. iOS 5 allows for only one string of text (i.e. no line returns) per shortcut, meaning you can't do a multi-line signature, but that's easy enough to overcome.
Here's a sample signature, followed by the procedure you'd use to create it:
Rick Broida - Hassle-Free PC
FB: facebook.com/hfpc Twitter: twitter.com/hfpc
Because of the aforementioned one-line-per-shortcut limit, you'll actually need to create (and use) three shortcuts to insert a signature like this one. Here's how:
1. On your iPhone, go to Settings, General, Keyboard, Add New Shortcut.
2. In the Phrase field, type the first line of your signature. In my example, that's Rick Broida - Hassle-Free PC. Then, in the Shortcut field, enter sig1 (meaning "signature, line 1). Then tap Save.
3. Tap Add New Shortcut again. This time, enter the second line of your signature in the Phrase field, followed by sig2 in the Shortcut field. Then tap Save.
4. Repeat the process for the third line, and call it sig3.
Get the idea? Now, when you're done composing an e-mail, just type sig1 to insert the first line of the signature. Tap return, then type sig2. Tap return one more time and type sig3. (Note that you have to hit Space after each shortcut to actually paste it in.)
It's not the most elegant process, but it sure beats typing all that info by hand. And if you want to get a bit more creative with your shortcut naming, you can easily mix and match signature lines. For example, you might call the first line namesig, the second socnet (for "social networks"), a third faxno (for "fax number"), and so on.