Despite my recent switch from Firefox to Safari 4—dudes, it really is that much faster—when it comes to managing my e-mail, I'm still a devotee of Mozilla's mail client, Thunderbird. I used Apple's Mail for a while, but ran into incompatibilities with my mail server, so I ended up switching over to Thunderbird.
So imagine my delight when I found out that just last week, the second beta version of Thunderbird 3 hit the Internet. I've just installed it, and have been overall pretty pleased with the new features, which include a new activity manager, a new Gmail-like e-mail archive functions, improved Growl notifications, more keyboard shortcuts, and a metric ton of bug fixes. Also, more cowbell.
Plus, there's a better, more Mac-like interface, with tabs and a new chrome color scheme. And maybe I'm just imagining things, but it sure seems zippier to me. Of course it's a beta release, so there's bound to be some issues here and there, but so far I'm liking what I see.