It's not free & it's not totally automatic, but BookmarkingDemon will save you a heck of a lot of time!
Yup, BookmarkingDemon saves you lot of precious time in posting to social bookmarking sites. Same with Social Poster which helps a lot in posting to good and well known social bookmarking sites...
Onlywire.com is free.. But it's an ass to sign up for all the sites and manually enter your login info. But at least you can use imacros or winautomation to automate that fr you.
www.socialmarket.com will help submit to many social media, bookmarketing and article sites and it is free. You will still need to signup for each account initially, however, just check the box to remember your login info and be sure not to clear your cookies. The next time you return your username and password will be saved. just login and post your content.
hey I have some killer software for this that lets me bookmark 70+ places at a time - it cost $150 but it was well worth it - called social submitter I think check it out
You mean something like this: http://www.socialmarker.com/ ? It's not fully automated but it speed up the social bookmarking process quite a bit.