You need to choose the quality web directories to submit to, check if the listing is human edited, well organized, and the PR and SERPs as well.
Directories still contribute to increase your rankings if you will post your link with very high PR directories like DMoz and yahoo. PR5 and below and free directories for me are useless. They will get your link then wait then reject. Lesson: Don't spend almost of your time link building on directories.
They do, but not like the ways they do 10 years ago. You have to submit to the best directories to get some boosts to your website's rankings. Google's becoming more and more sophisticated.
I do agree with previous posts. Big directories, which are trusted by SEs (DMOZ, Yahoo! Dir, etc) works great. But it's mostly because you get juicy link to your site.
Yes Directory Submission always worth your effort and if you choose High Quality Directory Like Dmoz, Yahoo Directory, V7n Directory, Vmoption Directory, Directory Critic Directory, Aviva Directory, SEO Friendly Directory 4 U, stpt.com/directory, lii.org, lanic.utexas.edu, directory.google.com, thomsonlocal.com, nationaldirectory.com, maven.co.il it's very High value Directory in Google point of view and it's back links always worth your Back links.
Directory is the place which always be on the top of the SEO strategies. It takes time to show result but you get high benefit for long time.
I'm not going to get into the PR discussion. But if you're submitting to directories for PR purposes, then check the PR of the page your link will be on, not the PR of the home page. You'll almost always see promotional language like: "Submit to my PR5 directory." But in fact the directory is not PR5 (or 7 or 2...). Only the home page is. You'll almost always be getting your link on a PR0 inner page.