dead.licious is a tool for verifying that all of your bookmarks in your del.icio.us, ma.gnolia, or Simpy accounts are still valid and gives you the option of removing or fixing those dead links

Unified bookmarklet for simultaneous posting to many social bookmarking services

Build a list of links through a simple AJAX web interface, published via HTML and RSS. Sort of a mini-blog for links (like my blog). Written in PHP5 and runs off XML files - no database needed. Includes the option to copy new links to del.icio.us and/or M