That would be a hub or if other webmasters can submit their free sites to it a link list.
This is my hub:
Porn Link World If you take a look at it, You will see that there isn't actually a series of pictures or anything like that, there is a list of links to my Free Sites and that is it.
Cute Teens Fucking This is a Free Site of mine, it has 4 pages, a warning page, a main page and 2 gallery pages.
Now if You look at Porn Link World, You will see that there is a link to Cute Teens Fucking and a lot of other Free Sites on it.
Porn Link World can't be submitted to Link Lists.
Porn Safe is a pretty much typical link list. But Cute Teens Fucking can and is submitted to Porn Safe. If You have a look at Cute Teens Fucking You will see a table of links to Link Lists, these are Reciprocal Links and to submit to a Link List You HAVE to have that Link Lists Recip Link on the Warning Page of Your Free Site. So I submitted Cute Teens Fucking to all the Link Lists that are in the Recip Table, I have mirrors of Cute Teens Fucking with other Reciprocal Links on them and Submit my free sites to around 80 different link lists.
You don't Have to have a warning page for Your hub, but Yo also want to sell stuff on Your hub, not Just Your free sites, so a warning page is essentially just another page to put ads on, if You want to have a warning page for Your hub. Free Sites MUST have a Warning page because that is where You will put the recip links.
Hope all this made some kind of sense