I recommend PTC's Windchill. It is 'web-based'/'cloud based'/easy to set up and great technical support over the past year.
I am not sure how I set the account up now, but can tell you the link:
FIRST Robotics Windchill
EDIT: The person to contact at PTC about setting up a Windchill account for your FIRST Robotics Team is Cosmin Pana -
cpana@ptc.com
The best part is that it can be used by any of the most popular modeling software plateforms (Inventor, SolidWorks, Pro/E - Creo, Catia, MathCAD, etc) with free plugins directly from PTC.
Also, this can be used for more than just CAD revision control. PTC also has direct plug-ins for windows and windows office suite. Now you can upload and control documents without ever leaving Word, Excel, PowerPoint, etc. There is also a plug-in for MS Project, but I haven't used that too much; I am sure it is great though.
Part of The RoboBees have been using Windchill for a year as a test bed, but I plan to launch it team wide in a few weeks. I have been using the direct plug-in for SolidWorks for sometime now, and have had zero issues.
Feel free to contact me through a PM, or on this thread so others can learn as well.