A few things, actually: movies, TV shows/cartoons, computer games, books, comics...
In no particular order:
The Lord of the Rings (recent movies): Mainly the richness & depth of the cultures. The lived-in, used, plausible sort of style that places & objects had (as opposed to the sort of "medieval setting, modern styles" in a fair amount of current D&D art). The Uruk-Hai influenced my notion of hobgoblins (along with Claudio's illustration of pseudo-Roman hobgoblins).
The Lord of the Rings (books): Using Tolkien's Elvish for my game's Elvish, Dwarven for Dwarven, and the Black Speech for Orcish. Naming conventions for elves, dwarves, orcs, and halflings.
The Lord of the Rings (Bakshi animated movie): Little influence at all, except for orcs. My campaign's orcs are more like those in this film, behavior-wise; whereas the hobgoblins are more like the Uruk-Hai from Jackson's films. Even the respective related soundtracks for each group fo characters fits: the more martial tones for hobgoblins/Uruk-Hai of Jackson's films; the more tribal/primal tones for orcs/orcs of Bakshi's film.
Record of Lodoss War (original; not Chronicles of the Heroic Knight): Bit of the feel. Bit of the good vs. evil element. Awesomeness of the dragons.
Masters of the Universe: Skeletor, ala Claudio's rendition of him on his website, for the big bad evil lich.
Thundercats: Mumm-Ra elements (incorporated into the aforementioned Skeletor-esque liche).
Ultima series of CRPGs: Some plot elements, bits of the Shadowlords from Ultima V for some unique monsters (mixed with LotR's Ringwraiths & Zork's Grues), some of the items.
Zork series of computes games: Spell names for item activation words (like "Rezrov" for a wand of knock, or "Frotz" for activating a item's light spell power); Grues (as mentioned above); anachronistic humor.
D&D Cartoon: Warduke for a "boss" villain (though using Dungeon's Warduke stats).
Star Wars (all 6 films): Jedi & Sith (minus midichlorian nonsense) for paladins & blackguards. Gen. Greivous for inspiration for a villainous Thri-Kreen NPC. Jango/Boba Fett for a bounty hunter/assassin after the party.
Conan the Barbarian (movie): For a grim-n-gritty feel to the setting. The snake-worship Thulsa Doom cult-elements for the Yuan-Ti. Akiro (Mako's wizard character) as an influence on the "feel" of Wu Jen IMC.
Myth Adventures series (books): Like with Zork, the anachronistic humor. Also a bit for the way/feel of other planes/dimensions.
Many more influences, but these are the ones that come to my mind ATM.