Kevin Kelly just released the third edition of True Films. This book has one page reviews of 200 of the best documentaries available. Each review has a few screen captures and an indication of where to rent or buy the films. With a Netflix subscription you can probably rent 80% of these movies.
I've watched many of the films he lists in the book; they are all awesome. Some are even life-changing. None of them have been boring.
Happily, Kevin is testing out an free, ad-supported version of the book. You can download this version from his site as a pdf.