While most webmasters will know of sites like Digg, stumbleupon etc - did you know there are actually masses of Social bookmarking sites out there. Now we all know that Digg is notoriously difficult to get noticed on (but it can provide some decent traffic through Digg searches) so the other social bookmarking sites (certainly niche ones) should offer a more reasonable target.
The ever wonderfull http://www.searchengineguide.com/ has an excellent piece on social bookmarking sites and links out to a variety of lists rounding up some of the best ones out there.
Check the link here http://www.searchengineguide.com/laycock/010829.html