An important indicator of a good quality web directory is whether it sells site-wide links (links to external sites that are repeated on every page, usually in the footer or sidebar).

A powerful link to your site is one that is relevant - from a unique page covering the same theme as your site, with text including related keywords and linking to other similar sites. This is the type of link that is worth paying for in a directory.

However, the value of a directory listing is diluted if there are completely unrelated links on the same page as the link to your site. And, because they are repeated on every page, site-wide links make every page look similar, so they can end up in the supplemental index.

eWebPages.org is a quality paid web directory that has no site-wides, not even the extremely common ‘Template sponsored by…’ or ‘Powered by PHP Link Directory’ footer links. It also has high PR on all its internal pages (PR 6 home page), even down to the third level categories (e.g. the Web Directories > Niche Directories > Entertainment Directories category is PR 4).

They charge an annual review fee, which is quite expensive, but worth it for the quality of the link back.