Web directories like the Open Directory Project DMOZ provide a searchable source for websites organized by categories and sub-categories. Maintained by humans (at least the reputable ones) who act as editors and make sure the submission is accurate and worthy of listing. It's a massive undertaking to maintain a directory and why some require a fee for being reviewed. The premise being that you pay a fee and it does not guarantee your site's inclusion. When considering using a web directory or blog directory to publicize your site look it over and see if the categories are related to your industry.

Google Page Rank is also a good indicator of 'trust' in the directory. Directories do not take the place of search engines and are really not related except for being on the Internet. Directories provide a grouping of like web sites edited by humans vs. search engines that use automated programs called robots or 'bots' to search and spider a web site. Search engines then analyze the results using algorithms to filter the raw data into a index. Search engines are 'looking' at keywords and phrases to make decisions on categorizing web sites. These results vary on the search engine and the special sauce they use in their algorithms to provide relative search results. That's why search engines like directories even though they are commonly used to spam a search engine with non-relative links. Although that does not make all directories bad. Pick ones that are relative to your site's content and have human editors. It's not as fast and can cost you some money but does help. Reciprocal links are not something you should engage in nor free widgets. You should be aware that this is a common link building method for building authority to the directory. Unless you wish to promote the designer or directory which is not unheard of. Just be aware that you are promoting the directory and would you want your good name associated with a spam directory of pharmaceutical off shore suppliers, ring tones and work at home sites.