The Steampunk Trilogy by Paul Di Filippo
Steampunk (comic book series) by Joe Kelly and Chris Bachalo
The Difference Engine by William Gibson & Bruce Sterling -- the designs of Charles Babbage lead to the wide usage of mechanical computers in Victorian England. (See difference engine)
League of Extraordinary Gentlemen 1898 by Alan Moore
The Grand Ellipse by Paula Volsky
Pasquale's Angel By Paul McAuley?
Jack Faust by Michael Swanwick
Perdido Street Station by China Mieville
Age of Unreason Trilogy by Gregory Keyes
Castle Falkenstein : high adventure in the steam age by Mike Pondsmith
A Nomad of the Time Streams by Michael Moorcock
Infernal Devices - K.W. Jeter
The Sundowners Series by James Swallow
Homunculus by James Blaylock
L'équilibre des paradoxes by Michel Pagel
Lord Kelvin's Machine by James Blaylock
A Transatlantic Tunnel, Hurrah! by [Harry Harrison]? -- an alternate history novel written and set in the 1970's in a world where the American Revolution failed and the British Empire is still going strong. It has a nice mix of technologies advanced or behind ours, with high powered lasers used for drilling, while Babbage engines are used to do calculations for sub-orbital flights.
Queen Victoria's Bomb by Ronald Clark -- in the mid 19th century; a physicist gets the idea of isotopic separation after seeing pebbles graded by size on a pebble beach, and makes an atomic bomb. He intends to use it to end the Crimean War, but it never gets used, and no difference is made to history.
His Dark Materials series by [Philip Pullman]? -- fantasy/alternate-universe science fiction with a quasi-Victorian setting
The Diamond Age by Neal Stephenson -- A cyberpunk adventure in a nanotechnological future, with much of the action in a neo-Victorian society
From the Earth to the Moon by Jules Verne
20,000 Leagues Under the Sea by Jules Verne
The Time Machine by H. G. Wells
The Ablest Man in the World by Edward Page Mitchell