If you use Firefox 3, you can set it up so that it launches FlashStuf Mail whenever you click an email link on the web! To do it, first log in to your account, and then paste this code in the address bar of that tab (and hit Enter):
Click Add Application, and you’re all set! To keep it this way, simply click an email link and then pick Gmail, and check “Remember my choice for mailto links” (you can change this option at any time through your Firefox preferences).