Audiosurf
Dont need to bother debating how awesome it is.
What songs have you found to be pretty good?
The other night I played NIN - Just like you imagined, and it was really intense.
Other good songs were:
NIN - pilgrimage, only, beside you in time
Aphex Twin - Bucephalus Bouncing Ball (REALLY hard. constant tempo changes)
Conan the barbarian OST - Wheel of Pain, the horn of dagoth (I think)
Terminator 1 title song
Tomoyasu Hoei - battle without honor or humanity (Kill Bill OST)
Fun Loving Criminals - Scooby snacks
Kenji by Fort Minor is the only one that stands out in my mind as being surprising. Almost any metal or techno with a high BPM will given you a hell of a ride.
boo 
it would seem audiosurf can't handle 70min techno tracks. too long
I tried:
Duality - slipknot (suprisingly nice ride)
Cold - Static-X (There is amaxing bend in the middle where it slows down, its fun 
)
Mt. Saint Michel Mix + St. Michaels Mount - Aphex Twin (amazingly dissapointing even on ironmode and ninja level its almost entirely uphill....wtf!??!)
Sad but true(orchestral version) - Metalica (quite nice, it works well with the algorithm and all the key notes are picked up on)
Last Legs - Valve (my fave from the ep2 soundtrack, I had it extracted with cgfscape. it gives a really laid back track)
At the heart of it all - NIN(technically by Aphex Twin) (sucked awesome song though)
Starting over - Korn (nice gental ride - I'm #1 in the world on pro level )
Bitch we got a problem - Korn (Also world #1 for pro Realy good rides, this one is all downhill and has a loop )
I can't remember what else I tried but I can remeber that most static-x songs make nice tracks
I've tried:
U2 - Elevation --> a pretty pleasant ride
U2 - Vertigo --> I didn't really like this
U2 - Beautiful Day --> the best of all attempts, this track got a nice point were you hear almost no instruments, and AudioSurf made that point the top of a hill, which suited the song very nicely
Madonna - Ray of Light --> This was also a nice song to ride, great switching between more quiet and more extreme parts. I did this one twice.
Unfortunately, after that my demo ran out. And since I don't have a credit card, and I don't see myself explaining to my parents what I want, I will never get the full version.
"Duct Tape is the answer."
Jedi knight you may be, but a master yet you are not.
Creed - One last breath
Works amazingly
'A Better Place, A Better Time' by Streetlight Manifesto was a pretty good ride.
I also played Aphex Twin - Bucephalous Bouncing Ball (and most of the Come To Daddy album)
I haven't played it since Monday, but I think I'll give Mr. Bungle a try since their music tends to change a lot throughout a single track.
One song I played that was surprisingly fast was "All is Full of Love" by Bjork. It seems like kind of a mellow song, but I had trouble keeping up. I think something about it tricks Audiosurf into thinking it has a lot going on.
Just did Aphex Twin - B.B.B. and came second globaly fro pro. It was quite leisurely and not realy that interesting even if there were a few moments where the track stopped then sped off again (I do mono, which makes moments like those tricky)
1. Anything by me. 
2. Command and Conquer series soundtracks.
3. AMBIENT MUSIC. Holy crap, the slower and more droning the song is, the faster and more insane audio surf goes. It's a strange phenomenon.