I'm currently running Fane of the Drow as a Living Greyhawk Adapted adventure. It's been pretty fun.
I make extensive use of the maps in my regular D&D campaign. They've been really great to provide interesting terrain for my players to interact with.
In particular:
Mithral Mines (Fane of the Drow) makes a great generic cave/tunnel location, and my players have seen it several times.
Likewise Forest Road[/b] (Fields of Ruin) is great for encounters on a road. My players have also seen a lot of this one (and the similar map from Red Hand of Doom).
I just got Dragonsdown Grotto the other day, and already the Clifftop Lair and Dragonsdown Grotto maps have proven useful.
Hmm. At present, I have 21 of these maps... they're not all equally useful, but they're a great timesaver and do more to present involved terrain than I can easily show on a battlemat - especially for wilderness encounters.
(21? Fane of the Drow: 4, Hellspike Prison: 4, War Drums Starter: 4, Fields of Ruin: 4 Dragondown Grotto: 4, Dragon Magazine/Drow Outpost: 1)
Cheers!