Checkout Wesco http://www.wescovan.com/products.asp for some good rigging information. Especially their guide to wire rope termination is nice. (link: http://www.wescovan.com/catalogs/WireRopeTerminations.pdf)
While the information offered is available at other locations, some of the stuff here is unique, though ment for objects much larger than we use in theatre.
But I still think its kind of cool and fun to look at some of the huge rigging hardware that they can make.
Also www.thecrosbygroup.com has alot of great resources as well.