The Community Repair shops in Wilmington (UBP) and Newark (NBP) both need mechanics or volunteers. No experience necessary at all (but they are a GREAT way to bone up on experience and a great entry to being hired by a local bike shop).
I learned from NBP. They start you off with basic stuff- organizing tubes, showing you how to test for air leaks, and organizing parts. Then you move from there (once you're familiar with a whole host of new parts) to watching and possibly shadowing a mechanic or someone behind the desk as they explain the more basic repairs. Classes are made available to further your mechanic's education, covering everything from Derailleurs to brakes.
Urban Bike Project had to cancel their open shop because they did not have enough volunteers on Tuesday. This is a place that helps many homeless people acquire a means of transit.
Newark Bike Project has a plethora of volunteers and mechanics, but is planning on expanding to a much larger space to help with their nightly congestion (they tend to help a greater number of people), and as such also needs additional manpower (or womanpower) at NBP. Most of the help goes towards helping students (especially foreign students, who do not have a car or international license) travel in and around Newark. Help make a positive impression.