What do you people do for gaming when it comes to mice ?
It'll depend on what type of games you play and your gaming style. For most people an inexpensive, lower end Logitech will be more than sufficient. I thought I was in that demographic until I got a Razer mouse. The customization options are so amazingly convenient and useful that I could never go back to any mouse without comparable features--there certainly are other companies that make mice with similar features too, but most don't seem to provide the Mac support, though limited, that Razer does.
If you're into FPS, it seems the best mouse now is one by Mad Catz, called the R.A.T. 7 (or R.A.T. 9, if you want the wireless version). Read some reviews and watch the site's vids on it and you'll come away with the strong impression there's nothing better for a demanding FPSer. Downside is that there's no Mac drivers, so the things that make it amazing won't work for you unless you Boot Camp.
If you're into DoTA style games like League of Legends or Heroes of Newerth, or any MMORPG, the Razer Naga appears to be the best. I'll most likely get it. Looks like it has limited Mac drivers, but I have a Windows system too, so if it can allow me to transfer configuration settings while in Windows to the Mac, then I'll get it for sure.
Meanwhile I'm using the Razer Orochi. It's incredible. It has features I never thought I'd use, but I'm using them all. It has 7 buttons, and again I'm using them all. There is one feature in it that's not working, but I can't tell if it's a Mac driver issue or just me, so I can't really recommend this mouse with total confidence. Been communicating with Razer Support for about a month over it.
And if you want wireless, be aware there's 2 types: RF wireless (which requires a little USB dongle) and Bluetooth. The latter is "truly wireless" in that it requires no USB attachment--100% clutter free. The Orochi is one of the few Bluetooth gaming mice out there, and the one with the best reviews.