Social bookmarking provide websites with tons of backlinks, which Google, Yahoo, and MSN love.
In fact, backlinks are one of the first things that the search engines search for while evaluating your site, so needless to say that the more backlinks you have,
the higher youll rank.
Social Submitter is a powerful submission tool with many integrated additional functions to help you organize your submission process.
Here is key features from developers site:
All posing process is automated so you can easily submit the whole site
Supports most popular social networks and bookmark sites (Digg.com, propeller.com, furl.net, del.icio.us, folkd.com, bibsonomy.org, dzone.com, mister-wong.com).
Allows you to control your submission process using command line.
Multi-threading architecture allows you to submit posts as fast as your Internet channel can.
CAPTCHA processing module.
Proxy support (proxy with authorization also supported).
Posting result logging system (include link grabbing system).
Automatic crawling and submission of all web site content
Synonimizing feature ({first|second} constructions available).
Site database updating every 2-3 days.

Social Submitter developers team have done a great job of creating automated posting procedure for a large setof social and bookmark sites.
Everything was done to make the software capable for submitting a page of a site (and even the whole site) to lots of social networks and bookmark sites within a couple of minutes.
Everyone can download a demo and try out the basic functions of the application, during three days.
After purchasing the program itself, you will need a set of accounts, registered in social networks and bookmark sites.

My experiments have shown that there usually are 5 or 10 dead sites.
Development team of Social Software sad that the social network sites can be down for some time, and basically several dead links in the database is a normal situation.