There is always the Neighbours from Hell games. They're as casual as can be and do have some puzzle elements....plus they were published by JoWood...

I think you can play Lumines free. (on PC)
Though its from wild tangent, so you might want to be careful. I think they've cleaned up their act recently, but i couldn't swear to it.
Gametap has a pretty good selection of puzzle games on their free service:
http://www.gametap.com/video-games/free-games/puzzle-games
Mr Driller is fun.
Bust A Move.
Super puzzle fighter
I got really addicted to Blast Miner. It has 2 modes, an action mode like tetris (which i thought was poor) and a puzzle mode which i got totally hooked on. Its similar to World of Goo in concept though, so you might not like it. (use timed explosions and physics to reach the goal).

they are good games, and they are games I'd like to see on GOG!
Lumines especially!
please, vote for items on the wishlist!
any place that has puyo puyo and the incredible machine rated lower than Dr. Robotniks Mean Bean machine is EFFED UP.