How about a ring... and the characters need to destroy it?:P
Seriously now, there are a lott of good quests on the wizard of the coast site. Do a search for free adventure.

I recommend 'The ettin's riddle'
There are so many possibilities that I thought know where to start. I suck at making a list of idea's though. besides, I don't have the FR setting book yet so I'm not familiar enough with FR.
How about letting the players play through BG and all of them are Children of Bhaal?
