I had a load, but I can't find the site I got the from. Try this one if you haven't seen it yet. It's good fun.
http://www.gamerebels.com/game/518/The-Dead-Case.html
It's not the ideal site for it. What happened to the official flash games site?
And then I used to use a page called Mandy's Hint PAge on weirdweb... and she had collected all these ace games and added hints. I like the adventure and role players most.
There's one called The Battle for Wesnoth which is fun. It's a fantasy turn based wargame. Google it; I don't remember the website. Downloadable.
Here's a forum for it:
http://www.wesnoth.org/forum/viewforum.php?f=3
This is pretty fun too; 20 questions vs. an AI. No download needed (I think).
http://www.20q.net/
This is a good geography quiz game:
http://www.craziness.com/games/play-geography-game-usa/
These are kind of cool murder mystery puzzles games.
http://normandcompany.com/STICKMAN/