It's been, what - 3 years? 4 years? since Reporting Services was released and I JUST stumbled upon this feature thanks to Chris Baldwin.
If you end up in the unenviable position of having to reverse engineer a complex report that you didn't build and want to get a feel for the structure of the report itself, the SSRS add-in includes a Document Outline window (see below) which will nicely document the structure of the report - You can see all the data regions, report items, etc. in the report WITHOUT having to spelunk around in the report itself. Combine this "new to me" feature with the Property window, and you can neatly and efficiently browse and change multiple properties on multiple report items in no time: Just click View | Other Windows | Document Outline