MS Mice
I really like the Intellimouse Explorer 3.0. Really fits your hand well; like someone said, it doesn't seem all that great at first, but it really grows on you.
BTW, in that range of MS Mice, although the new bluetooth mouse is really awesome, it doesn't work in OS X yet (or any other OS besides XP SP1, due to Microsoft's straight pushage of it's newest flagship OS, plus it's own bluetooth adapters...other adapters and Windows combinations don't work at all..).
As soon as the bluetooth mouse comes out, I think it would behoove you to check it out--it seems like it's almost molded for your hand, specifically. Great recessed thumb part, and the mouse just looks uber-badass. Great tracking, too.
Check it out, man!