i use a Logitech G9, I love the thing. the only way to describe it is sex for your hand xD it has on the fly DPI changing, you can make the scroll wheel do the *click* *click* thing or have it free roll. And there are interchangeable weights which make it glide perfectly. I picked it up from Tiger when they had the price marked down to $55 rather than the usual $80, i splurged a little bit cause i built a new gaming system but jeeze is the money worth it.
normally just use the trackpad, muti-touch kicks ass!! But for gaming I use the a logitech MX1100, it takes up a usb port, but it's big for my "Goofy" ass hands.
I got a Logitech Air Mouse back in December. It is the most unusual mouse that I have ever owned. I does take a bit of getting use to moving the mouse in thin air....it is great. I have several cats and they park themselves on my computer desk. They know when I use to use a conventional mouse that I'm not paying attention to them and they would park themselves on my mouse pad. NOT ANY MORE, I JUST HOLD IT IN THE AIR AND CONTINUE ON WITH MY BUSINESS. It is the most amazing mouse I've ever owned. Cudos to Logitech.
at the moment i'm using a microsoft mouse on my computer i've used the might mouses on mac at school before it horrible i feel like i can crush the mouse in my hand :S