I have this one. It's the Wacom Bamboo.
It's got 4 customisable buttons at the top, which are very, very handy. I've set 2 of mine to change the brush size in Photoshop.
Then theres a kinda circular shaped mouse pad at the top used for zooming in/scrolling.
This can be used with either your finger, or the pen.
The actual tablet itself is also very good. It's the only graphics tablet i've owned, and also one of the best peripherals I've ever bought.
Would definately recommend this tablet.