Bookmarking Demon used to be the best but to be honest it's a waste of time nowadays. The major search engines ignore links from social bookmarking sites that can be autoposted such as Pligg and Scuttle. To get any benefit you will have to manually post to major bookmarking sites.
if your site runs on wordpress, there's a nice plugin called auto poster... it features only minor social bookmarking sites, but it can help.
but demon is just a demo only where can I find some autosubmitter for social bookmarkings? I cannot find a good one one search engine.
I am also looking for one... I dont want 100% automated... a semi automated social bookmarking tool that can help me bookmark more faster...