Ok, so you have an iOS device, and you’re a man/boy/woman/girl/homosapien on the go, right? You’ve got multiple email addresses, and each of those email addresses has it’s own signature, right? You HAVE to have different signatures, because those different email addresses are used for different reasons; for instance, you don’t want to email your great-granny Frannie with the email signature that you use for your I-get-prescription-drugs-from-Canada-and-sell-them-for-super-cheap-in-The-States signature, right? What a ruckus that would cause!!
So as you probably know already, iOS doesn’t yet officially support multiple email signatures (as of iOS version 5.0.1). There are a lot of quick little tutorials out there that show you how you can have multiple email siggys using iOS’ relatively new Keyboard Shortcut feature, but they all suggest using a Keyboard Shortcut for each line of each signature, as the Keyboard Shortcut feature ignores carriage returns (for those too young to know what a “carriage return” is, look it up). So, I came up with what I feel is a much simpler way of doing things. Less taps in an email = more time playing Angry Birds, right? (FYI: I don’t get the draw of Angry Birds, but maybe I’m weird.) Ok, enough of this blabbering, read on to find out THE EASIEST way to setup multi-sigs on your iOS device. And you’re welcome in advance. 
FYI: The Evolution Of The Web infographic doesn’t seem to play nicely with mobile bowsers.