I do like traps and puzzles in dungeons. Only I’m terrible at making them up on the spot, and rarely have the time or creativity to make really good ones. The ideal puzzle should be something that you don’t have to mess with, pose some real consequences if you fail, and grant something pretty good for success — a treasure, a way around some obstacle, some other magical effect, etc. The “Alabaster tower” has some pretty good examples of puzzles — you really don’t need to solve them, you could just avoid the stupid tower. I usually go the other route and make puzzles things you have to solve to escape a dead end or avoid some immanent danger, because a time limit makes for more tension and prevents the players from overthinking things. I guess my favorite example would be simple logic puzzles of the sort you find in Smullyan’s books. The problem with these though is that they might be tough for one person reading a book but a group of people are more likely to have that guy who has heard it before, or is good at logic puzzles, or something. I threw a Smullyan type puzzle (three boxes with inscriptions, not all of which can be true, open one and get a treasure, open the wrong one and something bad happens) into a very early dungeon in my first D&D campaign, and it worked pretty well because the thief discovered it while scouting and had to solve it before a timer ran out. The player was pretty clever and figured it out. He got the treasure and did not share it with the party, the beginning of a trend that led to the character’s expulsion from the party! He also snarfed the box with the trap (an evil spirit was in it), and carried that box around for months. When the character re-emerged much later as an NPC, he still had a wraith-in-a-box, which would have been an awesome surprise except for the fact that party had protection from going when it finally got opened. Drats.
The ideal trap in my opinion should be something totally avoidable but which goes off if you are careless, hurried, or greedy. There is a fairly perfect trap in the “Anomalous Subsurface Environment” described here. I don’t think I”ve come up with any quite so good on my own. When I use traps they are more likely to be jokey (a lever in Telengard, if pulled, releases a swarm of insects onto you, etc.) or very cliché (yellow mold that looks like gold or gold dust, sinking rooms, illusionary floors). I suppose part of the problem is I’m still learning how to fairly adjudicate traps! All too often I forget about a trap and the party no longer has a clear marching order, or I forget how trap finding works in C&C, etc., and either the trap is unfairly unavoidable or too easy to bypass. But in theory I do like traps, and think they should be distributed about equally with monsters as the guardians of treasure.
At this point I should confess that I really like the Grimtooth’s Traps books. There aren’t many actual traps in them that I’d use, but I really do like the presentation (system neutral traps, clearly drawn). If only they had some that were not quite so gonzo.