One recent entry into the free pornography website market are Thumbnail gallery post sites.
These are free websites that post links to commercial sites, providing a sampling of the commercial site in the form of thumbnail images, or in the form of Free Hosted Galleries—samplings of full-sized content provided and hosted by the commercial sites to promote their site.
One of the early Gopher/FTP sites was at tudelft and was called the Digital Archive on the 17th Floor (List of websites founded before 1995).
This small image archive contained some low quality scanned pornographic images that were initially available to anyone anonymously, but the site soon became restricted to Netherlands only access.
As a rule, these sites sort thumbs by category and type of content available on a linked gallery.
Sites containing thumbs that lead to galleries with video content are called MGP (Movie Gallery Post).
A linklist is a (frequently) categorised web list of links to so called "freesites*", but unlike TGPs, links are provided in a form of text, not thumbs.