Submitting to Directories
By getting a listing with important directories you get two advantages. One is that it really helps increase you PageRank rating on Google and other search engines. As the larger directories get plenty of hits (in the millions monthly), you may get interested people to hit your site.

It is extremely important to be listed in the two main human made directories, Yahoo! and the Open Directory (http://www.dmoz.org).

But you should also try to get listed in other directories such as Looksmart, which is important.

A link from a free directories helps to increase your PageRank, so you might as well try to get listed in as many places as possible. You can also submit your site to regional directories for your area.

Link back to the directories, as this may help a little and some require it.

Try to get a link in an appropriate category from About.com. Because About.com has a large amount of quality links it is a very important link to get.

Search Engine Directories
We have one of the best lists of Directories and Search Engines on the Internet. This list give instructions on how to submit to the search engines and directories on its detailed list.

Search Engine Guide (http://www.searchengineguide.com/)
Beaucoup (http://www.beaucoup.com/) has a list of search engines and directories.

If you pay to make your listing more prominent from a free listing this may help get you more hits on the directory, but it will not help you increase your PageRank on Google.

Major Directories

Yahoo! Directory (www.yahoo.com) - A listing here is extremely important as this is one of the few sites that have a PageRank of 10, along with Google.

Open Directory Project (www.dmoz.com) - This is the largest directory done by humans and is an important site to be in. It is compiled by volunteer editors who take care of a wide selection of subjects that they index. You may have to submit several times before you are indexed. It may take a while to be indexed. It is free. The Open Directory Project has a page rank of 9/10. Other important web directory and search engine take information from them such as Google, AltaVista and others

Froogle.com - This is the product search tool for Google. You can place your product for free and update them with a data upload every month or so. This will also help your products to be shown in appropriate spots in Google and searches.

About.com - This is a large site with plenty of links to a large amount of general information. It is considered to be an important site with a PageRank of 8/10 on its homepage. It is done by human editors who I am sure get a tremendous amount of information submitted to them. If you are lucky enough to get a listing from them you may have to wait a while for them to put it in. I had a link from About.com to my Agra and Taj Mahal pages. I asked for a link several times for my Vegetarian-Restaurant.net site, but have not received one yet, even though this site is easily one of the top five web sites on this subject.

Business.com - Does annotated links to some excellent resources. PageRank is 8/10 on homepage.

Trade Association Directories - May list you for free, but you may also have to pay for a listing. This is a good site to be on as it may be considered important by Google.

Submit technical papers to Web sites such as Bitpipe www.bitpipe.com

Business Directories

Submit site to general business directories. Some major ones are Business.com (www.business.com)
Allbusines.com (http://www.allbusiness.com)
Yellowpages.com (http://www.yellowpages.com)