If the content I found after signing into Body Mod Girls is any indication, the term "mod" refers to any little modification to one's body. Sure, this is technically true, but on a site with such a name, wouldn't you think that a babe with one little nipple piercing or a star tattoo on her wrist is a bit of a gyp? The good news is that while there are those here, there are also chicks with loads of pussy piercings or and/or lots of body art as well. It should also be noted that the site is really just a section of the large mega-site XXX Raider Pass.
It seems to work this way: XXXRaiderPass has loads of content (mostly nonexclusive) that they tag with multiple niches. Then when you select a site like BodyModGirls, you are presented with all the content that fits in that niche (tattoos, piercing, etc). The dates would imply that they are updating a few times a week and at this point there are 170 videos and over 900 photo sets. The pics look good, but the movies range from poor to average in quality and can only be streamed and downloaded in Flash format.
The Raider mega-site is made up of many other sites/sections and they are all included with your membership to Body Mod Girls. There are over 20 of them and they cover various niches, from fatties to busty babes to squirting lovelies. Now, because all the content is tagged with all the niches it fits into, you are going to find plenty of overlap among the sections. But you will find loads of content throughout the network. And although much of it isn't great, there is some good stuff throughout as well. The network adds some value, but probably not enough to make it worth it.