The Crossroads of the Aether
Stardust is a fantastic Steampunk film, including Air pirates who harvest lightning. Not the best of storylines, but the Steampunk elements make it well worth watching.
Jonah Hex is another good one. Again, not the best of stories, but it has Horse mounted gattling guns, and Crossbows that fire explosive bolts. It deals with the idea of Superweapons in the US civil war.
As I do recall, Disney's animated movie, "The Great Mouse Detective", based on Eve Titus's Basil of Baker Street books, was done in a steampunk fashion.
Yes yes, Basil the Great mouse Detective is a great movie! What a plot, replacing the Queen with a clockwork replica. It has it all, airship vs hot air balloon battles, a fight to the death on the hands of Big Ben, Sherlock Holmes' bloodhound, and a fight scene in a toy makers shop where the clock work toys form part of the weaponry, and the main character has all the eccentricity of Holmes condensed into a small mad, mouse. Loved it! Check out the gadgets at the start that work through his forensics. the smoking machine and the print maker especially.
The Great Mouse Detective was quite good. To an extent, Young Sherlock Holmes was passable and a bit too Hollywood for its own good
I have recently viewed a 2010 movie I purchased at a dollar store. Entitled Sherlock Holmes , it starred Dominic Keating and Gareth David-Lloyd. The story was a bit steampunk as it had mechanical monsters, automatia, and flying mackines. Not a big budget blockbuster, but pleasant enough.
Aloysius has recruited me to help with the all-night movie marathon at the Symposium. Here is a list of pretty much all the steampunk and Victorian period movies (and a few documentaries) I have so you can make any suggestions about what you would like to see.
Le Voyage dans la lune (1902) and other Georges Melies films, 20,000 Leagues Under the Sea (1916), Nosferatu (1922), The Lost World (1925), Dracula (1931), King Solomon's Mines (1937), King Solomon's Mines (1950), 20,000 Leagues Under the Sea (1954), Around the World in 80 Days (1956), Journey to the Center of the Earth (1959), The Time Machine (1960), Mysterious Island (1961), First Men in the Moon (1964), Zulu (1964), The Wild Wild West, Season One (1965-1966), Jules Verne's Rocket to the Moon (1967), Chitty Chitty, Bang Bang (1968), Warlords of Atlantis (1978), The Great Train Robbery (1979), Time After Time (1979), The Adventures of Sherlock Holmes (1983), Castle in the Sky (1986), Without a Clue (1988), Mountains of the Moon (1990), Nadia: The Secret of Blue Water (1990-1991), The Casebook of Sherlock Holmes (1991), Bram Stoker's Dracula (1992), Wild Wild West (1999), Atlantis: The Lost Empire (2001), Murder Rooms: The Dark Beginnings of Sherlock Holmes (2001), The Time Machine (2002), The League of Extraordinary Gentlemen (2003), Last Exile (2003), Steamboy (2004), Van Helsing (2004), Van Helsing: The London Assignment (2004), Victorian Cycles: Wheels of Change (2004), H.G. Wells' War of the Worlds (2005), The War of the Worlds: An Historical Perspective (2005), Emma: A Victorian Romance, Season One (2005), Doctor Who: The Next Doctor (2005), The Mysterious Geographic Explorations of Jasper Morello (2005), The Amazing Screw-On Head (2006), The Prestige (2006), The Ruby in the Smoke (2006), Emma: A Victorian Romance, Season Two (2007), The Golden Compass (2007), Wormtooth Nation (2008), I Sell the Dead (2008), The Shadow in the North (2008), Sherlock Holmes (2009), Creation (2009), The Young Victoria (2009), The First Men in the Moon (2010), Around the World by Zeppelin (2010), Burke and Hare (2010), Nickel Chilldren (2010), The Extraordinary Adventures of Adele Blanc-Sec (2010), The League of Steam, Season One (2010), Bartitsu: The Lost Martial Art of Sherlock Holmes (2011), Hugo (2011)
And, with the wonders of bittorrent I have added Zulu Dawn (1979) and Hysteria (2011).
I'd also cite "Nausicaä of the Valley of the Wind" and "Brazil". Both are great films irrespective of their Steampunkery (and Dieselpunkery, in the case of "Brazil") and were influential in my introduction to the genre.
The Mutant Chronicles was sorta dieselpunk in flavor
I heard that Bioshock Infinite will have alot of steampunk elements
I do love wild wild west although it is much maligned. The hellboy franchise also incorporates steampunk aesthetics although it is set in modern times (I wasn't too fond of the second one based on story but the steampunky goodness was still there) and as everyone has mentioned, stardust is fantastic in every way.
I CAN'T BELIEVE THIS WASN'T MENTIONED! I probably looked over it in the thread. :-P
Hands-down: The Watchmaker's Son by Whitestone Motion Pictures (2008). It's short but good.
Scroll down to the brain and click on the watch. Another they made was a diesel punk variation of the Tin Man. That is called Heartless.
Whitestone Motion Pictures does short Indy films. They're really, really good, especially the editing. While not Steampunk, their Candy Shop is a little freaky. Oh, and they also do US Southren historical shorts too.