You've probably noticed that there are few, if any, ways to market your site that you can expect to work for a good length of time. In other words, you do one method and get some results from it, but if you don't redo that effort, your site will disappear again.
I've heard that article marketing is one of the best ways to focus your efforts for long-term results. As long as people keep picking up your articles for their sites, you can get ongoing benefits indefinitely.
Directory listings is another option, but I question how effective it really is (except the biggies, of course - Google, Yahoo, MSN, etc.). Smaller directories come and go, your links get removed and in many cases, never even make it into the directory.
There are 3 questions to this:
1) What methods do you use that do not require constant weekly or monthly attention for them to continue to work?
2) How often do you have to repeat this method for it to keep working?
3) Which methods have been most effective for you (boosted traffic, sales, sign-ups, etc.)? Please specify which benefit you received.