I used to follow a blogger called Caroline Middlebrook, who was a former software developer. Turns out she quit blogging and developed a software package called Imautomator, which submits your links to a number of free social bookmarking sites. The free service allows you a daily quota of 10 links to be scheduled for submission to 15 social bookmarkting sites.
Not a bad deal, if the package is effective, because it will help increase the number of links your site has with outside web sites, which in turn, improves your Google ranking and makes it easier for users to find you.
I'm not recommending the service yet because I don't know how well it works. I'm not even sure if, by automating this task, I'm in breach of some Internet etiquette ( if the social bookmarking sites would consider my links SPAM). But if it does work, it would save me a lot of time and effort in my online promotion efforts.