PopURI.us provides a tool to check at-a-glance the link popularity of any site based on its ranking (Google PageRank, Alexa Rank, Technorati etc.), social bookmarks (del.icio.us, etc), subscribers (Bloglines, etc) and more!
The results are presented nicely, all in one page, and looks something like this:
It also features a little widget to allow you to share this information on your blog.