One of my favorite tactics is stripping the players of all their posessions, and forcing them to think their way through a problem rather than relying on their "toys"...

Traps? My favorite were the old "Grimtooth's" traps books... One of my favorites involved a dungeon where rotting, locked doors were common. The trap was basically a weighted sash within the door, with a guillotine-style blade on it. If the door was opened 'correctly', the trap wouldn't trigger. Pity the poor fighter who thought he'd save the time by kicking it in, though...

M