I found 6 Glitches so far in Tony hawk's Project 8 for the Xbox 360. ( And I got it 2 days ago!)
Glitch 1:
The Grind LaunchSkatepark: If you grind, and force the grind meter to the way of an open space. When the meter goes to the way, BAIL! You'll go flying like a cannon and a minimum of 7 bones are broken^^
Glitch 2:
Vertical WallrideSchool (before you blast the gates to the Slums): If you approach the fence in the back near the two kickers. At about a 40-51 degree angle and you wallride. You'll wallride vertically. LOL
Glitch 3:
Invisible Bank DropSame place in Glitch 2: If you get off your board and approach the left kicker, and move up against the fence, you'll see your skater float. Jump and bank Drop, you'll do a bankdrop and pivot on the sidewalk, and sometimes bail, and get stuck in the fence
Glitch 4:
Wallride SpawnSame place as Glitch 2-3: If you approach the hidden bankdrop and wallride, against the fence, you'll float, and once you hit the banner on the top of the fence, you'll spawn infront of the two kickers.
Glitch 5:
Hidden RailMain Street(near the cheese ramp): If you go near the black pavement about 1-8 inches away from the sidewalk, and you stall or grind, you'll stall or grind on the black pavement.
Glitch 6:
Area ChangingCapitol/Main Street: If you approach the garden which is near the Capitol, and you go to the Capitol steps, and then bail halfway through the gardens, The Area Text will say "Main Street" and quickly switch to "The Capitol" when you're really in the Main Street ^^
Well, that's it, I'll post more, when I find more.