So you want fighty/thinky puzzles, am I right?
Here's one I'm currently using a variation on with my players. It doesn't seem like a puzzle at first, but when you get down to it, it is. My players have not figured out how to stop this guy yet, and call him the "Annoying Respawning Ranger"
Stop Following Us
"You meet up with a ranger of some description. He seems friendly enough. He strikes up a conversation, of which you don't remember the details, strangely enough (replace with whatever you feel the conversation was about, or whatever.) However, you do notice that this ranger's attitude soon changes for the worse, and he attacks you."
After they kill him and move on, he appears again a couple rooms later, pissed off, completely fine, and with any equipment he expended in the fight earlier (I use a poisoned spear, which returns to his hand after throwing it. You might want to use wands, a bow, etcetra). No matter how they kill this guy, he comes back. They cannot take any equipment from his dead body (my version of the ranger is undead, and self-cremates each time he dies; think of your own variation on the theme), so they can't weaken him for the next time, except for if they use a certain method (they haven't learned how to stop his spear coming back in my game, but leave hints to the method in the chat he has with them the first time.)
The goal? Stop this guy from attacking you. The trick is to somehow incapacitate him, AND leave him in a safe, secure, nonlethal area. Because if they tie him up and leave him on the floor, something might kill him, and he'll be right back...
Here's a little trap my DM used on us back in a 1e campaign
"You walk through a door, and suddenly feel a wrenching feeling; your vision becomes blurry, and you lose consciousness."
<Separate the players. This is important>
Now, make a description of a different scene for each player. My DM used a pub for myself, but he used other, more nightmarish settings for my fellow players. Basically, the challenge is figuring out that the place you were sent to is actually illusionary; in the game I was playing, each player essentially became an NPC for the other players (more accurately, they would be portrayed with a different body and voice), and several of the players who were in more threatening situations than I began attacking each-other; don't allow a save until they notice.
Mapmaker, Mapmaker, Make me a Map
"You each enter a 40 ft by 40 room. <Hand each player a map. Each map shows the same maze, but with traps, monsters, and two other things of your choice in it, respectively> You each see a different view of the room. Now, cross it."
Basically, each player gets a map. The maps don't need perfect separation of information; just don't repeat more than one section between two players. None of the players can say or explain in any way (the walls simply absorb chalk or any other form of writing, and if the players try to explain, drown out their words) what they have on their maps. Intentionally make the traps and monsters rather painful; secretly record any damage players who don't know about the monsters/traps take from said monsters/traps. Now, basically, players have to defend their team-mates from threats their team-mates don't know about, or somehow get their allies to deal with it (if, let's say, the party illusionist is able to see some of the monsters but the party warblade isn't, creating illusionary monsters on top of the real ones is a perfectly legitimate way of getting the warblade to fight them. Just as long as the illusionist doesn't let the warblade know that wasn't a real monster. Because then, that method won't work...) A lot of notepads will be passed from player to DM.
I've got a couple others, but I'll have to sum them up.