For example, in one map the RPG was placed on a far ridge. Players capable of strafe-jumping could jump on the ledge, others had to jump, grav-grab it and suffer some falling damage. Smart players would toss an explosive up on the ledge and pick up the falling presents.
Together with the thread about aim maps, this got me thinking about using physics more creatively. One thing I could think up on was emulating a sort of capture the flag mode, by rewarding players with points for dropping certain items into certain places. For example, there's a crystal in a map and whoever drops it in a fountain gains 5 points. The crystal glows very bright so whoever has it is pretty visible, much like any other ctf, and that player is somewhat hindered in his reaction time due to carrying the crystal.
Another thing is using items to activate traps or doors/bridges, such as in dm_lockdown, except with portable items. Think of power cells that eventually respawn at certain places. This could be used to unlock access to a powerfull weapon or a strong position, but one thing's for sure, it has to be worth the hassle.
I've also played with objects tied to length_constraints to make them deadly yet stay in place. And in my current map dm_mudanchee I've placed some items on a swinging platform and some just below a walkway, on a tiny ledge, waiting to be grav-grabbed.
So I wondered, how can we leverage the use of physics to a next level? I'm sure there are more ways to have fun with physics...
Make some maps around it. We need some more proper custom maps. 
), and that's a pity I think. A case of restrictive design, over-controlling the player just to make sure they all get the same experience. Easy trap for designers I think. Not that that happens only with puzzels or so...