Directory submission lists
When you first want to get your site launched, or later when you want to increase its popularity, you will probably consider directories. Several sites offer lists of directories that are free to submit to, and most also show the Page Rank of the sites.
What they don’t usually show is the Page rank of the pages within the site, and in a directory that has many sites listed in few categories it is easy to be several ‘links’ away from the home page, where search engines may never visit.
The other problem for the good people that maintain these lists is that directories frequently change from free to paid after a few months of being in business, so keeping the lists up to date is a big challenge (hence I am happy to refer you to these links rather than maintain my own!).
Try the following (the list is edited when I find new ones…):
http://www.directorycritic.com
http://info.vilesilencer.com
http://www.auroin.com/directories/
See also the earlier entry on directory submission software
Remember: It is often suggested that you should submit to a few directories a day, rather than thousands at the same time, to give the impression of a steady growth in popularity of your site.