For instance, I received this vintage Ideale saddle in exchange for some vintage Brooks.
I received these beautiful dressguards in exchange for a spare saddlebag.
I even had some custom metalwork done in exchange for a basket. Other trades have included embroidery in exchange for a rear rack, collectible fountain pens in exchange for artwork, and products in exchange for photography.
A good place to start looking for bartering opportunities as far as bicycles go, is bikeforums. They've set up "For Trade" threads for different geographical regions, where you can list the items you have available and the items you are looking for. Here is the one for the Northeastern USA. I have been considering setting up something similar - but cannot think of a way to do it without it eating up too much of my time.
And while trades can be pre-determined and formal ("I'll give you my Item X in exchange for your Item Y"), they can also be a sort of reciprocal, whimsical gift-giving - like pen pals exchanging objects instead of letters: You send the person something you think they might like, and at some later point they do the same. There are no explicit arrangements or expectations, and that is the neat thing about it. I've had these types of exchanges with several bike people, and it's been really nice - my latest gift being the delightfully named "bike burrito."
These things have fascinated me for some time, so I was pretty happy to get one. It's called a "bike burrito" because - well, it folds up like a burrito.
The "burrito" is held together by a toe-clip strap, which can be easily threaded through the rails under your saddle. With the "epic" winter we are having, it's safe to say that I won't be using it any time soon - but it deserves to be seen!
Connecting with other bicycle-loving people from around the world can be fun, and can lead to all sorts of exchanges you would not otherwise have. What are your thoughts on developing a system to facilitate this? Would you find it helpful? What features would be useful? Would simply using the comments section of a post be enough, or do you think it won't work without a message board? Ideas welcome!