I started riding my bike to work a few years ago, and I'm looking to try and push myself towards a goal, while at the same time raising money for a good cause (see their statement here):
Bikes Not Bombs uses the bicycle as a vehicle for social change.
We reclaim thousands of bicycles each year.
We create local and global programs that provide skill development, jobs, and sustainable transportation.
Our programs mobilize youth and adults to be leaders in community transformation.