I'm a huge fan of the Gmail interface, and I especially like that its so easy to access from my Treo 650.
If I could change but one thing, it'd be the "delete all spam" function in the spam folder.
I try to keep my spam folder clean, and I love the "delete all spam messages now" button that appears at the top of the page. However, when I click the button, I'm challenged with an "are you sure?" prompt that requires yet another click. Two clicks to delete all the spam.
However, if I choose to select all messages from the selection menu (that's one click) and then choose delete (that's two clicks), I get the same result.
IMHO, the "now" function should be a one-click function, n'est-ce pas?
Maybe they have those lazy users with pages of spam in mind for the now function?