Adult Directory - Adult directories are sites that categorize porn sites for their users. Basically the same DirtyPeter. If your site is more niche or category oriented, submit it as a Link Site under that specific category.
Adult Search Engine - Adult Search Engines act like real search engines. No directories are to be submitted here. Searching for porn via queries should be the main focus of your site.
Adult Store - A site dedicated to selling all things adult from DVDs, sex toys, lubes, etc.
Adult Webmaster Resource - If you have a site or section of a site that is dedicated to adult webmasters and contains a variety of webmaster related categories, then submit it as a webmaster resource. Remember to submit a URL directly to the adult webmasters section, not the main site, unless of course the whole site is an adult webmaster resource.
AVS Program - These are the master adult verification systems. Not for AVS sites, but for AVS programs. (i.e. AdultCheck, CyberAge)
AVS Site - This is a site that is part of an AVS program.
Blog - Blogs that are posted to frequently. If your blog is inactive for over a month at a time then is it really a blog? No blogs will be accepted if their post frequency is less than once a week.
Free Site - This site is free to viewers and must contain at least 30+ images or 15+ movies organized into multiple galleries. Must be category specific.
Link Site - These are basically the same as directories, but I like to treat them as specific to a certain category. If you have a general link site submit it to the Adult Directory type.
MGP Site - Same a TGP's but specialize in only movie posts. Can be general or category specific. If category specific, select the corresponding category.
Movie Gallery <-- No Longer Accepting - Same as picture galleries, but specific to movies instead. Must contain at least 5 ten second clips or 2 thirty second clips. Must be category specific.
Picture Gallery <-- No Longer Accepting - This is the traditional and ever popular thumbnail gallery post. Not TGP site, but only a gallery. Must be category specific. Must contain atleast 10+ images.
Picture-of-the-Day - Basically POTD sites. Can be general or category specific. If category specific, select the corresponding category.
TGP Site - This is for TGP sites. Not individual gallery submissions. Individual galleries should be submited as such. Can be general or category specific. If category specific, select the corresponding category.
Top List - Listing of top porn sites. Can be general or category specific. If category specific, select the corresponding category.