Social bookmark websites are an easy way to get backlinks that will increase your PR.
It's especially true with some sites like Netvouz or Mister-Wong. You can almost be sure that the links you add to those two bookmarking sites will be noticed by Google. :)
I definitely advise to open an account with them as it's free. So you may get easy backlinks!
List of Social Bookmark sites (by decreasing effectiveness for SEO):