I never have enough miniatures, regardless of the fact I have more than I'll ever use. Won't be happy though until I have multiple copies of every monster in existence in my collection.
Also, despite having a vast collection of old Dungeon mags and every official adventure (and a damn lot of 3rd party 3E adventures, such as the DCC line), I'm always on the lookout for more, even if it is to steal a plot, trap, location or monster from it.
If the D&D crew (or a 3rd party creator I like) makes it, I'm at least interested in checking it out, and that usually requires owning it in some fashion.