I am considering doing other projects next. The one that I have been eyeing up the most is the Ruins of Castle Greyhawk merged with the Expedition to Castle Greyhawk campaign. This is much more problematic, though, then Ravenloft. The main reason is that the two modules have the castle in different timeframes, so that rooms that are shown in both have far more differences than did the ones in the Ravenloft project. Also, the latter campaign refers to the unmapped portions as having to fallen to ruin rather than maintaining their earlier appearance, and much less inhabited.
That would be an amazing project. It's pretty well known around here that I am a huge fan of anything Greyhawk and would love to see the Castle done in this style