As everyone who's *honest* will agree, there's very little money to be made in TGPs/blogs/free sites/etc. these days. As some of the above posts point out, there's a lot of free content available these days, but I think they're missing the point. The amount of material available isn't the issue--it's the lack of imagination.
What do new people in this business do? Oooh! Oooh! Blog! Or maybe an MGP. And then a TGP. They stay up for a year, maybe two, until the domain expires. Then they're gone. Seriously, read some of last year's GFY threads. Look for all of the 'check out my new site!' posts. Go check them out. If the domain resolves at all, it's almost certainly pointing to a SEDO page now. Those webmaster's finally realized that mimicking a successful business model is not enough: you need to set yourself apart. Sites like The Hun and Pink World make serious money because they were first and they got the majority of traffic during the dot-com boom. Their popularity means that most new surfers are going to find them quickly, whether via search engines, links, or word of mouth. Trying to take those customers away by offering the same style of site (usually with inferior links, such as TGPs of FHGs, usually all of the same set of models) will never work. You need to provide a new service, something that surfers haven't seen before! It doesn't have to be ground-breaking, but it does need to be on the leading edge. I've been doing quite well with
EveKnows, even though
AskJolene is the undisputed leader of adult searching. Why? Because the market isn't saturated yet! There are *very* few good porn search engines, so there's room for a newcomer to break in and build up a solid userbase. Compare this to TGPs, where there are hundreds of high-quality sites and thousands upon thousands of mediocre ones. Highly-specific niche TGPs, MGPs, and blogs still probably have some potential, but don't kid yourself about your new Teen Babe Wonderland site. It's been done by scores before you, most of them probably looked better than yours, and they've all failed.
So, here's my advice: be creative. Remaking a popular mainstream site as an adult site may work for the first few people on the bandwagon, but it saturates quickly. I doubt you're going to do well with an adult YouTube clone anymore--you're a couple of years too late. New blogs are a few years too late. TGPs are *several* years behind. Be creative! Do something exciting!
There's certainly still money to be made in adult, it's just going to take some imagination to make it happen.
Best of luck!