I was reading this week's Parade Magazine which is an insert in my local paper once a week when I came across this great program. Wheels of Change ships used bicycles (plus seas, wheels, and helmets) from US to Africa, where they are sold and rented at a low cost. School children and medical volunteers ride for free.
Here's how it works:
Go to http://www.wocinternational.org/donate/ and fill out the form. They will email you the details on where you can take your used bike and/or equipment for donation. Please give the volunteers time to get back to you.
You can also start a chapter in your community if you would like to help. Please see website for more information.