Some sites that may help.

There are many sites about which we don't know and even if we try our best to find them on Google they are kind of invisible at the concern keywords, so for that one must look for those keywords which has nothing to do with the site you are working on.

If you are looking for the social bookmarking websites or any other sites like forums which provides you a backlink and also boost up your traffic then it's kind of impossible to find those kind of sites by searching on the search engines. I mean you just cannot write something like "sites to boost my traffic which also provide a good PR backlink" Daa.... that's not a search engine can understand and then to gives you the exact site you want to have.