Directory submission is, in general, a good way to improve the
PR of your own site as well as drive traffic. There are many people offering submission to xxx directories across the web, and whilst the majority of these aren't worth the time of day, getting your article on a handful of respectable, high traffic websites will do wonders for your site in terms of
PR and backlinks.
It is a good idea to monitor the web for your article(s) to ensure that people are playing ball and leaving your name and/or links in tact. I have sadly come across numerous websites using my work without credit, and whilst the majority of webmasters have added my name/link as required, a handful have reported back to me that they have purchased the article!
Just be careful who you go with, make sure that they are reputable people with a good track record. Software is a bonus as it can save you money in the long run, but the cost of submission is so cheap these days it is often more convenient to pay somebody else to do it for you.