I think that one of the reasons I enjoy making these tracks so much is because you can work on one of them for a few hours (say, over a couple of evenings) and end up with something very polished and fun. It's a nice relaxing shift from working on FPS levels that may take many hours to weeks or months to get close to a finished state.

Trackmania Nations is a FREE version of the game, and is only limited in that it includes just one of the seven environments and four play modes found in the full game.

If you like racing games at all, you should download Trackmania Nations and try it out. Right now. Seriously.

If you're going to try out any of the tracks below, I recommend the first ones listed (for Trackmania United), only because they are more polished and my TM building skills have increased over time (and any of the Stadium Race tracks for TMU will work with the free version of the game).