FASA Studios - the official MechCommander 2 page; includes downloads and political background on the Chaos March.
Kasey Chang's MechCommander 2 walkthrough
Battletech home - the granddaddy of the Mech Universe.
ComStar - excellent historical overviews of the political situations and background in the MechWarrior Universe.
Written by relayer. Preserved here as part of the-spoiler.com archive. Original source: The Spoiler.