Psion: I haven't run that adventure, called Divisions of the Mind, but I did read it, although it was quite some time ago, so the following details may not be entirely correct.
See there's this Beholder, and he wants the adventurers to find out what the deal is with this Mind Flayer who lives in this floating crystal citadel in his territory. Of course, the Mind Flayer has secrets of his own...
I thought it sounded pretty cool, but it's for higher level PCs and mine aren't quite up there yet.
Dungeon magazine (and to a lesser extent, the advent of 3rd Edition) are what got me started running a game in the first place. Some of the adventures I read sounded like so much fun, I found myself wishing someone would run them for me! Of course, since I had read them that was now out of the question, so I decided, what the heck... and I started a campaign. I only have issues 79 and up, but I plan on rectifying that situation at GenCon this year.
Almost all of the adventures I've run have come from Dungeon. Here are some of the ones I enjoyed:
Evil Unearthed (#82): PCs investigating mysterious disappearances in a small hamlet uncover a plot by an evil cleric to unearth ancient evil (Hence the title

). Although as written the adventure has nothing to do with Tharizdun and his cult as presented in RttToEE, modifications can be made to provide some mild foreshadowing.
A Race Against Time (#81): Delayed blast fireballs placed in stasis and scattered around a city + a list of clues + realtime time limit = fun for all (or at least the DM

)!
Bad Seeds (#79): The PCs arrive at an out of the way inn late one night and find the place utterly empty come morning. Only some strange yellow dust and a dream of a dryad may lead the PCs to the missing patrons.
Valley of the Snails (#87): The PCs are hired to go looking for a missing ranger in a strange valley. The ranger has been struck mad by the poison dart of a local band of goblins. Lots of wilderness goodness for outdoorsy PCs.
Cradle of Madness (#87): This one is a great lead-in for RttToEE if toned down a bit (it's for 5th level PCs). What appears at first to be a kidnapping turns out to be a much more diabolical plot to awaken Tharizdun.
I know there's more, but I guess I've rambled enough.
