These are both by Cmdr "Whiskey Nick" Triton. I love how he took the classic Jack-O-Lantern design and jazzed it up with just the right amount of rivets and metallic accents. Plus those hinged eyes on the right are too cool.
Or, for something a little (ok, a LOT) crazier:
Yowza! I definitely wouldn't want to meet this in a dark alley. o.0
My favorite part is the pipe legs; they're a great way to elevate your pumpkin and give it an industrial edge. (The plumbing fixture goggles are also a great touch - I think I'd use just one with a chain for a fun monocle.) Head over to GeekDad for a free .pdf with instructions on how to make this yourself.
Better Homes and Gardens has a roundup of no-carve "Junk-ins" with some neat elements. They're not exactly steampunk, of course, but there are still plenty of ideas to borrow. My favorite is the pumpkin coach:
Look at the tiny mice!! They're made of little gourds, nails, and upholstery tacks. Such a simple idea with such a huge pay off.
I also like this springy clock design:
Of course, now I want to install a working clock in a pumpkin. It'd be super easy with a craft-store kit - and they're battery powered, so you don't have to worry about cords.
Or, if you want a ridiculously complex carving challenge, how about this clock design?
Photo taken by Rebecca Paiva at the Jack-O-Lantern Spectacular
This "Junk-O-Lantern" is another that's more junky than steamy, but I like the idea of using wire spirals for hair:
Just use copper or brass wire for a more steamy look.
Steampunk author Cherie Priest bought this plastic pumpkin at a Wal-Mart years ago, so it's no longer available - but it's a great inspiration piece:
Instructibles user Yami Guru modified those ubiquitous pumpkin candy buckets into steampunk versions. I like how he used tea strainers for the eyes:
These two are actually custom toys by Steamwork Studios, but I'm loving the mismatched eyes and chest grates:
Space Boy Robot (who has some awesome robots on his site, btw) made this fabulous Jack-O-Bot:
Oh! And also this one!
Well, that's all I've got, my friends. Now, are you inspired? Good! Then go forth and steam up some pumpkins!! (And then send me pictures, 'cuz I want to see!)