TrackMania Nations Forever is now available as a free download!
TrackMania Nations Forever offers a new complete "Forever" version of the Stadium environment, a complete solo mode and 65 brand new, progressively difficult tracks…
Edited - JeffreyM: Edited link direct to download page.
Great game… not sure if this is the place to start posting free software cos there's just too much good free stuff out there, but this is worth a download! Great fun.
You can even create your own tracks to race on - which takes a fair while but is rewarding!