Directory Submission

Directories are different from search engines in that they are compiled by humans rather than indexed by computers.

Directories:

The most popular directory is of course Yahoo. Here's a list of 100 more directories that you can submit your site to for free from vilesilencer.com

I wouldn't spend too much time with that unless you have the time to kill. Maybe try the top 10..

Search Engines:

Obviously you want to submit your web site to the Google and few other search engines as well.

Ask
Lycos
Altavista
HotBot
Dogpile
AOL
MSN
Infoseek
GoTo

Better to take 20 minutes and do it by hand. Definitely don't pay anybody to "submit you site to 100 search engines."