You can toggle between the Table of Contents or the Index in the Reverb 2.0 output. For example, you can go to:

http://www.webworks.com/Documentation/Reverb/index.html#toc/

http://www.webworks.com/Documentation/DITA_1.2_Specification/index.html#index/

Clicking on these links will bring up that part of the help as opposed to the regular view.