I use Keyboard Maestro with AppleScript to replace @@@ with email+currentsite.com@mydomain.com. No iOS though

Wow, I've been annoyed for as long as I've had a smart phone that it never could input my e-mail in an easy way. And then it was this easy all along, thanks!

for vim, you just do

   :ab hn Hey there hackernews!

or whatever to define abbreviations. Honestly I mainly use them to correct things I commonly mistype or if the CapitAliZation of MyCompanyName is annoying.