It also has two trackpads (one in each side of the keyboard). But I hate trackpads, so I don't use them. So instead, I just had a plain old mouse on the desk in front of me.
The other day I got a little bolt-on platform for the mouse that lets it sit lower than the surface of the desk, which is nice; now I can use the mouse without moving my arm as far. This platform is a little sketchy, though, in that it's flat along one axis, but along the other axis it kind of bows up in the middle, meaning the mouse rocks/tilts. Also, I suspect that the fabric covering it will last about a month before it's all frayed around the edges.
I also just got an Evoluent VerticalMouse 2 (left-handed version). It seems like a good idea, but I'm not sure I'm liking this yet. The button layout takes a little getting used to: there are three buttons and a scroll wheel under your fingers, and one button on the other side, under your thumb. On the left side, from top (index finger) to bottom, the buttons are "left/right/middle", with scroll-wheel-press being "middle"; and the button under your thumb is "right". Which wasn't obvious at first, but kind of makes sense.
The problem I have with it is that I find it almost impossible to move the mouse without pressing a button. I don't know where to put my fingers to hold on to the thing to drag it around! Most of the time when I reach for it, I end up clicking by mistake, and when I'm dragging, I click the "middle" (bottom left) button all the time. I guess you need to drag with it cupped in the heel of your palm, but I'm not used to that yet.
I really just wish there was a version of the Kinesis Evolution keyboard that had a trackpoint and a scroll wheel instead of trackpads.
Update: Mostly I got used to it, so I can move it without clicking; but I have the bottom left button disabled anyway, since that's the one I click by accident, and I don't particularly need it.