> they do. they rock. :)
> Logitech Trackman Marble. don't leave home without it. :)

I used to use these on all of my machines, however I just recently replaced
them all with the Microsoft Trackball Opticals.  5 buttons + scrolly wheel,
works great with Linux, and way more resolution and responsiveness than the
Logitech.  Works great for Q3 too.  And the best part is that it's only $33
and not beige.

http://www.us.buy.com/retail/product.asp?sku=10255981&hdwt=30804&loc=14577