sv_gravity 1000 = This means that gravity will be ULTRA strong
sv_gravity 0 = This means that gravity will be gone, note you cant jump
sv_gravity 201 = This is the lowest you are allowed to have gravity set and still be able to jump
sv_gravity -1000 = This will make you foat up to the top of the skybox in the map!
would be a terrible cheat to have considering once he was floating he would have almost no control over his movements and would be a prime target to every sniper, mg'er, smg'er around. also considering that it IS in fact server controlled it in pretty much impossible for a client side mod.