When I had Gentoo on my laptop (a long time ago), I had Synaptics installed. I though that it simply add to the touchpad the possibility of scrolling, but I usually had annoying problems (scrolling when I didn’t want, going back on the web browser…) and eventually I uninstalled it. These days I’m just using the touchpad instead of using a mini USB mouse, just because I use the laptop on the sofa or on the bed and apart from my belly there isn’t any surface smooth enough to use it :P. But the touchpad alone is crappy when you do an intensive use of the computer, so I gave another try to Synaptics, and I was gladly surprised!