other player traps

Personally the best traps I see are the complete failsafes a room rigged with tnt but also contains your valuables and bed/anything else and has 1 secret "safe" entrance and is also well hidden.I would post a video of how I rig it up but fraps records 1 minute of video as like 2gb.

Also if your talking monster traps you can never go wrong with a trapdoor drawbridge with a pit of lava under them wired with redstone to raise all the doors simutainuasly. < (I know I didnt spell that right)

I like to have a shaft of water leading up to my floating base, and let people think that's the entrance (but it's not!!). Then, when they try and get up to my base, I flip a switch for a sticky piston which will close behind them, and then I watch through glass as they drown

special food blast: place a button connecting to a dispenser of food. then put a sign saying free food!. aaaannnndddd put some redstone leading to a tnt. sure... its obvius but there is food.

I made a small mine just under a lake, but left ores in the ceiling so that when someone digs it out, either sand falls down or water comes rushing in and drowns them. Probably won't work, or if it does it won't work too well, but it's good enough for now.