Trap use
I just want to see what other people do with their traps. Personally, I use them to protect all my loot, which I stash at the stairs to the previous level so that if I die, my bones at least gets all the rest of my crap. Mines I usually just set at some junction where I can get around them, but that an unintelligent jackal might still step on it.

I mentioned somewhere else that I keep the occasional mine I come across in UT for use on zombies. I don't really use traps much, though.

When I pick up traps, I never remember to put them down, and that tends to get one killed, so I never pick up traps. I think I'll try that intersection thing next time I play though, that sounds like a good idea. Even better with corners, since I never step in them anyway.

Be prepared, carry lots of mines and backpacks.
I haven't done it a lot, but when I see a uber-baddy coming, I like to set up a mine with a backpack on top. That'll usually just make the tougher ones mad, but you follow that with an adamant bear trap to keep them in one spot for the wands of striking, that'll do enough damage to finish them or weaken them enough to finish them up close. You could also backpack + beartrap + fireball, or mix in a wand. Secondary explosions certainly kill ME often enough. Time to return the favor! P.S. Learn from my mistake. Wands of fireballs will usually knock them out of the beartraps.