I wanted to point out a new feature I've added, since it might not be so obvious. It is designed to provide more feedback to MOC designers, as well as help you keep track and build a sort of portfolio of other people's MOCs you have built.
I have made several enhancements and added new features related to managing your LEGO collection. These will help make Rebrickable the best LEGO collection management tool around :)
You can now optionally group the results of parts and sets listings by a choice of fields, and filter the list with multiple selections at the same time. The available fields will depend on the page you are on.