sv_walkspeed #
usage: rcon sv_walkspeed "0-inf"
Sets the walk speed Default is 150. Very fun command because you can set it superfast and do just about anything 
 
sv_runspeed #
usage: rcon sv_runspeed "0-inf"
Sets the run speed Default is 250
sv_crouchmult #
usage: rcon sv_crouchmult "0-inf"
Sets the crouch speed Multiplyer Default is 0.6.  Set this to 0 and you cant move while crouching. Set it to 1 and you move just as fast as standing.
 
I believe theres one for jump hight as well but I'm unable to locate it 
