I imagine the best place to start would be Werner Cohn's excellent expose of some of the Good Professor's nastier connections. The fact that Chomsky claims that the whole thing is a pack of filthy lies leads me to believe that its probably 99% true (even a stopped clock is right twice a day, perhaps in Chomsky's case once a day).
Needless to say, Chomsky is quite well thought of by neo-Nazi and neo-Fascist groups in Europe (and America for that matter). This seems to confirm my opinion that Chomsky straddles the line between the extreme Left and extreme Right, combining elements of both. His closest mainstream political counterpart is proabably Pat Buchanan. In fact, a good argument can be made that Chomsky is essentially a paleo-Con. However, his longstanding support for communist and other Leftwing totalitarian regimes throws a bit of a wrench into the works. It does go a long way to explain how the politics of the Left and Rightwing extremes are merging more and more on issues like Israel, the War on Terror, and protectionism.