The May 2007 issue of "Cycling Plus" has the results of their most recent lock tests. As always, their tests show that any lock that has the work "Masterlock" on it is not actually a lock: it is a sign saying "Get your free bike right here".
The best (and most expensive) chain locks from OnGuard and Kryptonite have done well in testing by "Cycling Plus" and in testing by soldsecure.com. However, an eight pound or ten pound chain does NOT provide better security than a five pound u-lock, such as the Kryptonite Fahgettaboudit u-lock. I have no problem finding beefy steel poles set in concrete that are perfect for use with a u-lock...why use a chain?
www.soldsecure.com/Leisure.htm