On my trip back to the States last week, I took some of my megadungeon stuff along. I'm currently keying the 3rd level of the dungeon, and got from 18 rooms up to 100 rooms keyed.
But I only had my listing of Classic D&D monsters (a homemade document with most of the non-planar BECM/RC critters, plus some of the Creature Catalogue monsters I use a lot and some of my home-made critters thrown in too). For the past couple days, I've been going through my PDF collection of monster books, looking for other stuff to use.
There's a lot of good stuff out there, between Classic, AD&D 1E and 2E (especially the 2E Monstrous Compendiums of various campaign worlds and annuals), and 3rd party stuff like a PDF a friend sent me of White Dwarf's various creature feature articles (many of which are in the Fiend Folio, but not all!).
I feel like I'm swarming in monsters! And that's not a complaint.
I've had an idea to try and make a new monster every week here on the blog. That's my goal, anyway. 52 new monsters (or stats given to various non-D&D monsters like I usually do) in 2012.
Stay tuned, the first one should be coming up maybe tomorrow or Friday.