Post glitches you find in games whether they let you go to normally inaccessible areas, or any other strange stuff. Also tell us how to do them if you know how.

Two i recall are:

In Jak 3 you can fly over walls once you unlock the hover ability, and the sheild. Normally if you use the hover you don't fly, but float so you can't get really high, but if you start floating by hitting X twice, then O to activate the sheild, then X again You'll float higher than normal. So hit X, X, O, X, O, X and so on. Once you unlock unlimited Light Eco is when it gets really fun.

In Spider-Man 2 i found a way to have your health meter be empty but your still alive. Start a challenge (The Blue Markers), then get high enough so when you hit the ground you'll die. This is where it gets difficult. Fall to the ground, and right before you hit the ground, pause quit the challenge, and when it asks if you want to restart, say yes. If you timed it perfect enough, there should be a small delay between the time you select yes and the challenge restarts. This gives you time to hit the ground and die, but when the challenge restarts his health will be empty and he will live.

I'd say the ol' 'Halo 2 get out of the map' trick, I've forgotten how to do it but it's one worth posting. Made some fun minigames out of it too.

You mean warthog sword jumping?
Thats pretty much the only fun part of that game. Also the part in that over cast level where you jump into the tiny crease then uncrouch and boooom your in the sky.

That and the mysteriously fall through the floor glitch. I loved to 'butterfly' people.

in halo 1 on side winder i remember getting the scorpion up on the cliff and using the ghost to go outside the map

the gears 2 shield and shotgun glitch was unstoppable until the patched it =[

GTA 4 has tonnes of glitches. The most fun for me was the swingset trick.
You drive into the middle pole of any swingset, and then you sit your car against the left hand side pole, and wait for the BOOM! ;]