Second is the ability to easily manipulate large amounts of email. I mean, easily archive, make read, etc. any amount of email through search. I like to see when people follow me on twitter via email. I get an email everytime, which means there is a ton of email that I want to only look at once. Gmail allows me to go: Search:"Twitter", then "Select All", Archive. Now all that is out of my inbox.
But seriously, a good, no, great spam filter.
1 and 2 combined makes it a winner for me. :)
Every thing not beeing a "full-blown" editor should have bindings to support a subset of your favorite keymap. So those who like Emacs or Vi, or Wordstar for that matter, could leverage their habits.
I have a Gmail account, too, but I haven't found any Gmail-specific features I would use. Conversations or labels are neat and my spouse adores them. As for me I just don't care as long as my search box is working.
Edit: Ah, it keeps future messages in the thread out of the inbox too. Neat.
This ensures that I see all threads at least once, but if I'm not interested in the thread, I never see it again.
Has anyone else made the switch from this to gmail?
Keeps my life in check.