Books: Journey to the Center of the Earth is a good one and Around the World in 80 days, also The Time Machine by H.G. Wells, Tim Powers' The Anubis Gates, Homunculus by James Blaylock, and K.W. Jeter's Morlock Night and Infernal Devices, also The Difference Engine by William Gibson and Bruce Sterling; also, Terry Pratchett has elements of magi-steampunk in the background, and 1632 is sort of a reverse/round-about look at a lot of what Steampunk is.
Comic/Movie: The League of Extraordinary Gentlemen is an excellent example of Steampunk, even if the movie did suck.
Manga/Anime: There's actually a movie called Steamboy; Castle in the Sky and Howl's Moving Castle also count as Steampunk.
I'd go on, but I suspect this will be more helpful:
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