Bidding (Bid) directories is a common type of paid directories which works by using the following principe - the bigger the amount of your bid the higher your website placed relative to other listings. The advantage of bid directories is that you will get baclink to your site directly from the home page of directory. Submission into bid directories with high PR and attendance - will gain extra exposure and grow SEO parameters for your site. With the constant updating of content on the main page and grouping by categories - bidding directories are well indexed by search engines. List of the most SEO frendly bid directories you can find on this page.