Proogle is a new free SEO tool which displays Google search results with PageRank under each individual search result. This tool can be extremely effective for searching competitor backlinks using the link: function, and you can view 100 backlinks at a time by adding &num=100 to the address bar after you search. Please note that it takes a bit of time for the Proogle site to return results since it is under heavy load and has to collect a bunch of PageRank data.
Example Search Engine Journal backlink search
by Aaron Wall of SEO Book.com