One of the first things that I do when reviewing and evaluating an Incident Report that occurred in the U.S. is to note the state where the incident occurred. Then I turn to this fantastic guide [scroll down, pick a state] in an effort to understand both the cyclist's and motorist's actions in the proper legal context. International users please bring equivalent resources in your country to my attention.
A comprehensive listing of the "three-feet" laws for each state, with a color-coded key and a citation to the applicable state statute detailing the law.
PeopleForBikes started out in 1999 and now has over one million members. They have ambitious goals that I support. I personally became a member and donated to the organization last year.

I know that there are many other worthy resources out there and I will be adding to this list as I encounter them. If you would like to suggest a resource for the CCDB community, please do so here: submit a resource.