There will be more, I’m sure.
Thanks!
I get a lot of my unfinished wood here. If anybody’s got wooden gears, this place would.
Cloth belts would work for light loading. According to an old engineering book I have, the strongest, most durable belts are made from well tanned leather taken from the back of an ox, cut parallel to the backbone on the upper part of the side. Stitching is done with heavy cotton thread. The edges of the belt should be properly trimmed.
Tandy leather sells servicable belts that can be used for this.
Boston Gear, and most gear manufacturers will have brass gears. Expect them to be pricey. Bronze is more readily available and less costly. You might find wooden gears somewhere, but most are probably hand made. Here’s a video about one type. Wooden gears are probably limited to slow, low load applications like clockwork.
Is this a decorative or functional project?
That’s good, in the event the OP doesn’t have a dead ox handy 
There is a water powered mill still in operation (http://www.schechsmill.com/) not far from me. The belts were orginally leather, but I seem to recall there is some sort of synthetic replacement, but I don’t remember what it is.
Brian
Google industrial belts or industrial v-belts. You’ll find lots of belts to chose from, even old tractor belts.
McMaster_Carr is always a good source for anything industrial in small quanities:
Small Parts is good as well:
Here in the Colorado Rocky Mountains the mountain lions sometimes take down an elk. Maybe I can chase the big cats away and use elk leather. 
I’m building a replica of the Great Organ at Unseen University (described in ‘Soul Music’ by Terry Pratchett). It’ll have to be somewhat reduced from the description–even if I could get a 64-foot organ pipe I wouldn’t have a place to put that sucker. The organ will be functional (I hope) but only the reed section; the pipes will be decorative. I have this vision of rotating organ pipes over the top of the organ console–it’ll be fun! I’m thinking gears like these with a belt drive to a hidden motor which will be substituting for water power.
One of you engineer types: is there a diagram somewhere on-line that shows how to get two shafts rotating in different directions using gearing from one engine? I’m sure it’s simple, but I’m not seeing it in my head very clearly.
Simply driving one shaft from the other with a gear will make them counter-rotate. It can get more complicated than that depending on the conditions. Do you have more details? With more specific information you can get some of the finest engineers in the world to answer this in GQ.
I’d use rubber, personally - depending on the attachment, a fanbelt or similar.
Completely independent of Steampunk, there’s quite an active wooden automaton and marble run community online. I’ve lost my bookmarks, but “wooden marble run” and “wooden automaton” are good search terms. There’s all sorts of info on jigs etc for cutting wooden gears, and they’ll likely have commercial sources too.
Can’t help you there.
Just be sure to do an etched brass nameplate that calls it your “Mighty Organ”
and then a subscript that says “B.S. Johnson”
