I do the spin, it's pretty fun.
I also like to try to force the other guys into pit... it's a hard minigame, because they don't just let you do it--they fight back!
My favourite thing, though, is to tune the suspension--high ride, soft springs, low bound and high rebound (if I remember right) and the last 2 turns of Trial Mountain. There's dirt to the left of the left-hand turn (right before Pit IIRC) and a dirt ramp on the right of the following right-hand one.
So I get going real good through the dirt on the left turn... but I don't turn. I keep going straight as I can to hit the highest point of the ramp on the right. It's
awesome!! You fly through the overpass, and I've finished the race still spinning from that. It's a great jump to demonstrate how the game fudges its physics to make sure you (eventually) land on your wheels. I swear, one of these days I'll jump into pit row with this!
It only works on Trial Mountain, not TMII. Deep Forest, both directions but Deep Forest I, also has a GREAT ramp for this... right after a STRAIGHTAWAY!!