I like the aesthetic of Steampunk. I enjoy the concept that technology can be functional, well-crafted and...well...beautiful. The easiest version for the layman is the Disney version of 20,000 Leagues Under the Sea. Nemo's Nautilus nearly defines the technological style.
Strange examples, fine.
The work of people like Jake Von Slatt are intimidating and fascinating to me. He creates things that I would love to display in my living room - functional, yet art. A living room computer, for instance, that is not a generic beige box but is instead a wonder of brass, marble, leather and a cohesive whole.
Technically, the style is an alternate version of the Victorian era where technology took a different turn where steam and gears and airships took over and remained as the dominant technology. The Babbage Difference Engine is the computer of the day (large, mechanical with a myriad of moving parts) instead of our current electricity based computers.
It is a greasy, hands on world.
The natural expression of Steampunk in the popular culture can be seen in events such as the Maker Faire, Crucible Fire Arts Festival and even Burning Man (I am not hardcore enough for Burning Man). All are fun events, and I highly recommend them (except for Burning Man, I've never been (though it probably IS fun)).
Clothing aesthetic for Steampunk is varied. One of the best descriptions is
"Steampunk is what happens when Goths discover brown." (I don't know who came up with that, someone tell me and I'll credit them).
The clothing is corsetry, leather, top hats, riding trousers and, of course, goggles. No Steampunk ensemble is complete without a bizarre set of welding, aether filtering, essentially useless goggles (still, I want some!). The look is that of a twisted Victorian era.
There are some good stories set in Steampunk universes:
Leviathan - Scott Westerfield. It is a young adult novel set in a pre WW1 where the bio-engineering Darwinists fight the steam driven Clankers.
The Diamond Age (A Young Ladies Illustrated Primer) - Neal Stephenson. Not truly a Steampunk book, it takes place in our future but it captures much of the aesthetic and culture.
The Difference Engine - William Gibson and Bruce Sterling. Possibly one of the definitive stories. What would the world be like if the era of computers started 100 years earlier? What if Charles Babbage's Difference Engine came into widespread use?
Soulless - Gail Carriger. Victorian era story where Vampires, Werewolves and other supernatural entities love openly as part of society. Oh, and a good amount of steampunk as well.
I'm sure I'll write more on this later but I think this is a good start.