I am so tired of "sorry that name is already in use, how about these crappy names?" messages when I'm signing up for a service. Just use my email address... always my email address. It's guaranteed unique, and I can always remember it. All you need to do is build in a service that allows you to change the email address associated with your account if you need to change your email address for some reason.
If you disagree, you can find me on instant messenger as garythegaryowentheowen2062006