I use a thumball mouse for gaming - no pad for me, no tired arms, etc. Not for everyone though.
I used to thumball too ... swore by it for years ... untill i was forced to get a new keyboard last year, and decided to go wireless. (it was complicated, involved my then 5-year old nephew and a bottle of Hawaiian punch)
when my free mousepad (average 9x6 incher from roadrunner) proved to be too small for gaming - i.e. nasty slices in TW2k5 when the mouse fell off at the end of my swing, i went to Office Depot, and for 10$ picked up a 12"x18" Allsop pad with the blue raindrops on it ...
i used to swear that the thumball was the way to go for FPS gaming, as i made it thru tribes 1 & 2, all the UT games, and HL 1 & 2 with it ... and every other game i ever played since 98 ...
but now if i try to go back, i really feel there is a loss of freedom. it's really hard to explain.
I am thinking about one of those 30"x18" pads for work, so i can have a little wrist padding without having to have the gel log ... if newegg would ever get them back in stock ...