At Artengine, there was this very cool initiative called something like “Have a Part, Need a Part” or something like that. I believe it was initiated by Ryan Stec and it was a repository of parts and materials that people shared.
In our group we had something similar except were labeled and priced. The idea was if you had extra stuff (like when you order 100 of something but only needed 20), you can place some of them on the parts share. Other people who need the parts can avoid mail order plus you can reduce your inventory.
This was great for Arduino and electronic parts since those activities are so parts oriented. And it facilitated a bit of trading and sharing of extra parts.
Now we just join the google group (see the online link) or discuss exchanges at the meetups.