I too, want more Vile stuff!
WoTC's Call of Cthulhu d20 game has a bunch of vile and corrupt spells, creatures, items and gods in it with rules on how to adapt them to D&D. Great book.
The Green Ronin books Legions of Hell and Armies of the Abyss are both great. Mongoose's Demonology is okay but not really worth the extra effort to implement the new rules. AEG's EVIL has better, easier rules for summoning/binding demons, as well as a (poorly written) Demon Summoner PrC and a Bargainer PrC for those who wish to corrupt others and trade in souls for power (much better written). There are a lot of Infernal feats one can gain from pacts with fiends as well. Beware of awful typos as usual with AEG, however.
Check out Dragon #295 (red dragon on cover burning a castle) for Sean K Reynold's Gingwatzim in the Living Greyhawl Journal. These are ethereal creatures that can be enslaved on the prime as guards or magic items. A little DM work is necessary but they can be changed from air elementals native to the Ethereal Plane into demons, devils, daemons or other fiends of comparable power. Also in that article is Sean's "Catoboligne" demon, a sneaky non-Tanaa-ri used as guardians on the prime.
Green Ronin's Plot & Poison: Guide to Drow is awesome and has many vile PrCs like the Submissive and Dominant (for the S&M bondage crowd, LOL), as well as a Master Summoner PrC. New feats, new spells, new poisons, new nasty magic items (including a completely new and streamlined way to handle magic item creation superior to the core rules). Rules on how to create tortured magic items out of living creatures or undead, how to suck XP out of willing or unwilling subjects to powqer magic item creation, and more. A fabulous book; most of it can be adapted for non-drow use, too!
Fast Forward's Encylopedia of Demons & Devils II has PrCs, new spells and a ton of demon and devil lords, ladies and minions. It's pretty good.