Depends on directories but the main reason people submit to directories is to get backlinks to their sites. If its a well trafficed directory you may get your site indexed faster. There are dozens of directory lists on these forums. As a shameless plug, I have recently started two of my own. Please feel free to pratice on my sites since they are very new you may actually be helping me work out the bugs. If you mention you saw this post here I will upgrade your listing to featured for free. WebEasyLinks Com or BackLinks.Mediazene Com
Few community based blog directories like blogcatalog.com/ blogflux.com would help you to gain traffic too.
you get back links which are worth for getting back links. But only try to submit to popular directories coz if you start submitting to all then search engines think that you are just spamming.
Submitting to a lot of directories will get your site banned from Google. Choose only the best directories to submit to.
Make sure you submit your sire to quality directories. I agree that quality matters way more than the quantity.
Submitting your website on dirs will help you bring traffic as well as quality links for your website
What I think about is not concentrating on submitting your site to directories, but creating good content for your vistors to turn back. It is important to have backlinks for your site, but not waiting for that to bring you visitors back to your site. Try creating high quality content.