Source for small replacement parts, like...  

wooden button screw caps, chair leg caps, metal spacers, shelf pins, etc.
I came across this company when looking for a specific size rubber stopper with a hole in the middle that I could cut down for a cheap shock mount for a cheap Plycraft chair. Their service was great, they don't charge excessive shipping, and I LOVE their website.
Plus, they had some other things that I had a hard time finding in the past. Bookmark them if you think there's any chance you might ever need them, because you know you will not be able to remember them later. (And I will have forgotten by then, too, so don't think you can just ask me. Har.)
My favorite thing is the fast bottle opener for bartenders. I don't tend bar and I don't even open that many bottles, but it is a very lovely object and they photographed it well.
http://www.widgetco.com