Take off, eh?:
 In 2 player mode you can get OUT OF THE FENCE!! This works best in
 Winter Wonderland. If one player gets in a corner and the other
 player gets a lot of speed and hits the player in the corner you can
 knock each other out! 
 
 Yum: At the enter name screen, enter these codes...
 
 LOWRIDER - Stock car
 FIFTY - Hot Rod
 BEEFY - Monster Truck
 SPRINTER - Buggy
 FRIENDLY - Track 7
 SANDUNE - Speed Demon and Mud Runner Cup
 ALLTRACK - All 12 tracks
 
 PC version only (?)
 
 Hidden Stuff:
 When asked for your name, type one of the following:
   * CHEAT1
   * CHEAT2
   * CHEAT3
   * CHEAT4
   * CHEAT5
 
 Just enter one at a time. You'll get 4 hidden cars, no clipping, and
 access to all tracks.