Steampunk really isn't my style, though the art is cool in a very geeky way. Steampunk takes modern things like phones and computers and reimagines them in a sort of old-fashioned motif.
If you do like steampunk, but lack the time and inclination to turn your own computer into a steampunk masterpiece, you can get a cover that will make the transformation of your iMac for you. A steampunk guru known as Woodguy from Old Time Computer has a couple of covers for the iMac that turns the device into a Steampunk design.
The covers can be had in cherry with or without a marble base or Maplewood with a wood base. The covers are cool and leave the screen and webcam uncovered. Pricing is unknown. The cherry is called Shaker Style and the maple is called Maplewood.