I'm using a ~15 year old grey cloth RadioShack mousepad at home, works great.
Here at work, pickings are slim so I'm using two plastic pads that were gimmes. The teflon sliders on the mice constantly gum up with junk... it's either coming from the plastic or from me, which is disturbing in it's own right.
Anyhow, I think the cloth pads end up performing a cleaning role as well. And of course, they should be cleaned themselves occasionally...