Anime & Manga / Steampunk

Steampunk in anime and manga.

The Case Study of Vanitas is a steampunk vampire fantasy set in nineteenth-century Paris.
Although the tech is not the main focus of the series, D.Gray-Man happens to have a relatively good Science Division where everyone there operates by multiple flat screen television and massive steel plants. In the Victorian Era! And the chief of the Science Division creates enormous robots on a seemingly daily basis.

A majority of Ergo Proxy is set around a wind machine called the 400 Rabbits.
Fullmetal Alchemist, like Last Exile above, combines steampunk and Diesel Punk and adds a healthy dose of Magitek.
Last Exile is a mixture of this and Diesel Punk, with the Guild leaning more to Crystal Spires and Togas.
A number of works by Mohiro Kitoh are steampunk, though with a greater emphasis on the "punk" aspect. These include the short story collection Wings of Vendemiaire and his currently-running series Futago no Teikoku.
Nadia: The Secret of Blue Water is potentially the best known example in anime, being loosely inspired by Jules Verne's "20,000 Leagues Under the Sea". Everything from the setting (1889 France), characters and costume designs, to oceanic travel aboard phlebotinum powered submarines, and Zeppelins from Another World, adheres to a 'Golden Age' aesthetic.

In One Piece the Revolutionary Army seem to have a general Steampunk theme. They have steam ships, 19th century weapons, and British Navy-esque uniforms to counteract the more primitive pirates with their Devil Fruit abilities.
Princess Principal: With H.G. Wells Cavorite anti-gravity tech, pollution-filled London filled with factories, Dickensian poverty, and suave spy action, This is a Steampunk for The New '10s.
The animated adaptations of the Sakura Taisen franchise are full of steam powered mechs, beautiful young girls, and cherry blossoms fighting against hordes of mechanized demons.
Samurai 7 is a Feudal Future where giant steam-powered robots, spaceships (!), and Schizo Tech devices exist despite the majority of people living like Medieval peasants. The samurai have Charles Atlas Superpower abilities that put them roughly on par with Jedi and it all evens out.

It's hard not draw comparisons between Secret of Cerulean Sand and The Secret of Blue Water, due to the sheer number of similarities, including the titles of both series. Likewise, each is based off a work of Jules Verne^note and has a pervasive steampunk aesthetic. The key differences being, that Cerulean Sand is set in London and the desert is presented as if it were an ocean.
The version of Professor Moriarty from Sherlock Hound uses a variety of steam-powered contraptions. Some of them are fairly reasonable (a particularly large automobile, a steam-powered press for minting counterfeit coins), but others fall squarely into this (an airplane modeled on a Pterosaur or an amphibious paddle-boat with robotic arms).
The feature-length anime Steamboy is required watching for any steampunk aficionado.
Steam Detectives. Steam-powered cars, robots, etc, set against the backdrop of a city constantly fogged up; with villains using the dense clouds of steam as cover for their nefarious deeds. Machine Baron's motivation is collecting at least one of each kind of steam-powered robot. His episodes revolve around his attempts to steal the hero's Robot Buddy Goriki.
Much of Studio Ghibli's work is like steampunk... without the punk. In particular, Hayao Miyazaki is incredibly fond of Zeppelins from Another World.
- Also, for instance, the robot from◊ Castle in the Sky.
- For other instances: The film based on Howl's Moving Castle, Nausicaä of the Valley of the Wind (which tends to be more like Schizo Tech) and some bits of Ponyo on the Cliff by the Sea and Princess Mononoke.
The Trigun anime has this sort of aesthetic mixed with Space Western. This is due to the fact it is a planet settled by human colonists despite the fact it's one big desert with minimal resources. As a result, it has a lot of Schizo Tech and people having reverted back to 19th century attitudes as well as dress despite all manner of supertech.