gmail

I've been beta testing gmail for a few days now and I'm impressed! It's interface is clean and quick. With the keyboard shortcuts you can do everything you need to do without using the mouse (which will warm the heart of vi users). The automatic threading makes digging through a 'pile' of emails a breeze. I haven't made much use of the labels feature yet, but I like the idea behind it -- no folders, just tags. I just spell checked this posting -- the spell checker is integrated into the GUI in the most amazing fashion. Usability: 5 of 5 stars!