I'm currently reading Boneshaker by Cherie Priest which is part alternate history/part post apocalypic city story with Zombies and Sky pirates.
That's actually why I picked up Arcanum again.
What are some other really good Steampunk books out there that you'd recommend?

"Steampunk" Volumes 1 and 2, a very cool graphic novel set in Imperial Britain. If you can, find the original issues for video game ad nostalgia goodness.
"Fitzpatrick's War" by Theodore Judson. Post-Apocalyptic Steampunk megalomania written in the manner of a long lost diary, complete with footnotes from contemporary 'historians.'
"Scar Night," "Iron Angel," and "God of Clocks" by Alan Campbell. Also known as the "Deepgate Codex," these novels are a quasi-theological (don't worry, its not preachy) steampunk romp detailing the war between Heaven, Hell, and the offspring of both.

The Anubis Gates by Tim Powers - steampunk classic book. Not too steampunk in my option, but very good.
Pasquale's Angel by Paul James McAuley - not set in victorian era, but kinda hardcore steampunk propriets. Very good.

http://www.gog.com/en/forum/arcanum_of_steamworks_and_magick_obscura/if_you_like_arcanum_why_don_amp_039_t_you_try
I would love to play a game set in the Hungry City Chronicles (Mortal Engines) setting.

"The Diamond Age" by Neal Stephenson has a very steampunk vibe to it but it has nanotechnology in it. Still a wickedly good read, nonetheless.

Well, to make it simple, I'd say : READ ALL NEAL STEPHENSON !!
^_^
Oh, and William Gibson & Bruce Sterling's "The Difference Engine" is also a must read!

Not exactly steampunk---there's little to no machinery---but with an allied feel: the Garrett series by Glen Cook. ("Sweet Silver Blues" is the first book, all the titles have a metal in them.) Cross hard-boiled detective a la Nero Wolfe with fantasy, throw in Vietnam-era-like elements [long-term unpopular war (he began the series in the 1990s, so it pre-dates current events), increasing interspecies unrest].

There's Leviathan, by Scott Westerfeld. This is about as steampunk as it gets: bio-engineered living war machines on the side of the Darwinists, kerosene powered exoskeletons and engines of destruction on the side of the Clankers, and the son of murdered Arch-Duke Ferdinand in the middle on the whale ship Leviathan, all at the beginning of World War I...
Very sweet.

Not quite Steampunk, but close, is the Mercedes Lackey 'Elemental Masters' series. They're basically magic in a victorian/1900-1910 Britain.

Perdido Street Station, and it's sequels by China Mieville are very good.

I want to give another vote for the "Mortal Engines Quartet" by Philip Reeve. It has airship piracy and municipal darwinism for crying out loud!

Michael Moorcock's "Warlord of the Air" is probably classifiable as steampunk. Its the first in "A Nomad of the Time Streams" trilogy and mixes steam technology, alternative histories and has a mixture of interesting anarchistic, mysterious, and revolutionary characters.

Actually you should read the originals....the works of Jules Verne and HG Wells, the 2 great Victorian Science Fiction writers. It is amazing to me how many Steampunk fans don' do that..........

I really enjoyed the three Myst books ... even if there is less steam and punk ^^ but some steampunk belongs to every myst world I think, even if it isnt directly written.

I recommend Arcadia Snips and the Steamwork Consortium. It's a bit light-hearted for a "punk" book but it's technically free, so do take a look if you have time.
Now that I think about it, it might actually be a parody of steampunk...