Stumpedia is not really a social bookmarking site. It is more like a link announcing site. Nonetheless, there is a XRiot Stumpedia page which lists links submitted. The site does a very good job with drawing in a screen shot of the page being linked and providing a excerpt from the page. It does not categorize on the member’s page but does allow tags and categories when submitting as the links/pages are collected for a search function also.

A list of a few things that you might enjoy.