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I bought a Razer DeathAdder for Mac and I'm loving it. I've also used Logitech MX Rev. for a while and those are great as well.

But I'm a gamer, so. It's great for work too though, but you gotta game to take full advantage.
 
I would suggest getting the Logitech MX revolution. It's a bit up there in price, but it's worth it.

The MX revolution is a decent mouse but I think it's a bit to bulky as a notebook mouse.. If you wanna carry your mouse around you might wanna consider the VX revolution or VX Nano.
 
Yes the trackball scrolls everywhere. It's great if your in a cramped area and are unable to move the mouse itself.
 
The only thing about Logitech wireless mice is that they can have a few problems with OS X, particularly when you're using an application to map their buttons to commands, like USB Overdrive, Steermouse, or ControllerMate. I find that you sometimes have to disconnect and reconnect the USB receiver after unlocking the machine—if you don't, your cursor loses its "weight": it can't trigger hover events.
 
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