Yep! You can create your own by going into Options > Auto Text > BB/Menu button > New. You can choose what key strokes to input (like "zz", or "mm", or whatever you prefer), and then you tell it what that should be replaced with (your email address). Then just make sure you press the BB/Menu button and click on Save when you're done.
EDIT: You can also scroll through the Auto Text that is already in the phone. It already has so many Auto Text options that I wasn't even aware of until I scrolled through that list.
