Hrrrrmm, some of my favorites...
Château d'Amberville, as already mentioned, is a good one. Just requires a little conversion work.
If you're looking for a good buy, Kenzer is giving away their Coin of Power trilogy. All you have to do is pay the shipping. ($6)
For my overall favorite, though, I'll have to pick Penumbra adventures. They're from Atlas games. They have a special hardcover coming out soon, or already out, that contains Maiden Voyage, Three Days to Kill, Belly of the Beast, and In the Tide of Years. They rated 3.0, 3.88, 3.73, and 3.80, respectively. I would recommend staying away from Thieves in the Forest, as the editing is poor and is really only 5-6 encounters. The former adventures, though, are some of the best I've ever bought, both for ideas and actual game content.