When studying a Bible passage, it's easy to find help in a commentary, but it's more difficult to find cross-references in ordinary books. That's what CrossBook is all about.
When you read a book and find an exegetical cross-reference, save it in CrossBook. And when you're studying a Bible passage, select a book of the Bible and a chapter, and you will find all the cross-references that you (and others) have entered.
Anyone can search for cross-references, but only contributors can add new books and cross-references. Email James if you want to be a contributor.