These FIRST Robotics Team sites are filled with great reference materials.
Team 27-Team Rush
A set of resources compiled by a veteran team.
Team 234-Cyber Blue
Creator of clickFRC.
Team 365-MOE University
A set of courses hosted by MOE mentors to educate members.
A great tool for information on several different robotics topics.
Other Helpful Links:
NEMO – Non-Engineering Mentor Organization This website shares papers, presentations, and stories about the non-technical aspects of team management.