Continuing on the vein of their Research Beyond Google page, the Online Education Database has recently posted The Ultimate Guide to the Invisible Web, which looks like a really good resource. There you will find background on the concept of the invisible web, 9 reasons a web page is invisible, 10 ways to make invisible content visible, and how to access and search for invisible content. Good stuff!
Technorati Tags: research, invisible_web, deep_web