GMAIL ADD-ONS
I suppose that we shouldn't be too surprised that gmail has already developed a cult following. And some people just can't wait for Google to finish developing their product so they've put together a lot of unofficial add-ons -- e.g. a gmail POP3 client, a program that alerts you to pending gmail, an auto-forward that sends all your hotmail to your gmail account. Those are just a few of the applications I understand. I suspect that one of these guys is writing a program to use gmail to over throw everything Microsoft. It is a very powerful webmail program.

P.S. I like gmail -- slick. However, they haven't been giving me any more invitations recently. Sorry.