And also this is one more thread running up but it is not related to directories or Articles but it is Helpful for one way links : http://forums.digitalpoint.com/showthread.php?t=118195
Article submission has not returned a good roi for me. I built 12 different articles and submitted each one to over 50 article submission sites. Some of the reasons why this doesnt work well are the sites that pick up these syndications TEND to be spammy, no name, low worth sites. People also strip out your links so they take your content but dont leave the links back to you. I would say directory submissions are going to be your best bet but when doing linking you need to vary your method up. One of the best kind of links would be a relevant website linking to you which 9 out of 10 times is not a directory unless your site is a directory. Use arelis or seo elite or web ceo o get link partners. Email them and ask them for a link. Something I havent seen mentioned here is Social Bookmarking. That will get you a permanant link if you create an account with each social bookmarkig site. These sites are PR 7-PR9. This topic is pretty big in the seo community right now. Also create a squiddo account, create a wiki user page, create a myspace account and setup a pagfe all about what your site is about and link to it. Some things you need ot look for when having a link placed on someones site is are they CACHED and INDEXEd to name a couple things. To get a ton of information and a link guidline go to www.directoryrevolution.com
Here is a great list of methods at SEObook, 101 to be exact. Link Building Wiki has a great list of resources. I also have pretty comprehensive lists of article sites (289 sorted by Pagerank), directories (427), software submission sites (492), and tagging sites (124) at my blog.