The Treasury of Scripture Knowledge (TSK) is a time-tested Bible help that avoids exposition and interpretation in favor of straightforward comparison of Scripture with Scripture. The TSK can be thought of as the most exhaustive collection of margin cross-references available, but it goes well beyond merely listing additional verses to read: it helps you define words and phrases from within a Bible verse using the Bible itself. In my opinion, if one were required to choose only a single written work in addition to the Bible for studying, the TSK would be the best option.
At first glance, the TSK can appear cryptic. However, once you understand the basic structure, it is quite easy to use, and with a little bit of time will help you define a coherent theology on just about any Bible subject.
The old SSModules web site, containing free downloadable library material for SwordSearcher, as been merged with the new SwordSearcher Forums. See the new module repository here.
There are plenty of extra books you can download and add to SwordSearcher. Plus, you can vote for your favorite modules (including ones included with SwordSearcher). SwordSearcher users who have created books can even upload their modules to share.