On the ruins map, if you are hit by a smoke on the bridge, you can fall into the immulsion, unlike other maps, where there is an nvisible wall to stop you from falling. You die of course, but still.
Sometimes, you float towards the cover at the corners(where the sniper and torque spawn if you have not customized the weapons) and you land on the cover. Doesn't usually work though.
Also, on the canals map, if you throw a smoke at the right time (presuming you're caught in the blast), you can shoot literaly 40-50 foot in the air, and stay there. I don't know if you can move, as I haveonly managed to get the bots to do it once a smoke has been thrown.
Both times on the bridge where the grenades spawn. I think you have to be hoping over when the smoke blows up or something.
sXe