bicycle trailer hitch - Google Search
seatpost hitch - Google Search
IC 349 Integrated Manufacturing Project
Haulin' Colin Bike Trailers
A customizable trailer that can be pulled by virtually any bike.
DIY Bike Trailer - Portland Maine Bicycle Commuting (Portland , ME) - Meetup
I saw this design on a folding bike and thought it awesome. I used to hitch my bike trailers with a lashed inner tube, but this is faster and more convenient. Works very nicely.
really cool tilting bike.
HH Max Cargo Bike Trailer. (Doubles as a hand cart)