By submitting to directories your will get some backlinks which will increase your SERP and PR. Well, don't expect wonders, directory links alone won't help you rank for competitive keywords. It's always a good idea to diversify your link profile so try to build / buy other DoFollow links as well.
There are a lot of directory links in this forum. Just look around, I found already 2 lists, one contains 1000 directories, the other 2700+. BTW, does anyone own an automatic directory submission script/software? Can you give it for free?