My developed sites are made up of content that I either write myself, or collect myself. I don't mind posting my best known site; it's certainly no secret and I'm rather proud of it (it gets 70k uniques per day in season, all kinds of press, and countless tv and news websites link to it, not to mention the State of Michigan) -->
www.michiganfireworks.com. And although I've automated as much as possible, believe me, it's a LOT of work. I have to find the displays, and verify them, and write the descriptions. Plus I've done a ton of SEO work on it for the search engines, and it's taken me a few years, but now it's nicely positioned at #1 for almost every reasonable search term in Google, Yahoo and MSN. Of course, that wonderful traffic does tend to drop off rather sharply on July 5th (ork ork)...
Right now I'm developing my search engine for Halloween related scary stuff - I have 50 domains, one for each state, that begin with "HauntedInWhateverState" For that I'm using a Google Custom Search Engine, and hand-picking the sites in the search engine myself, and labeling them as to what kind of attraction they are. I can do some tricky stuff with the DNS to make one website with 49 subdirectories look like 50 different sites (it helps to own a hosting company).
I have some more projects on the burner for when I get done with Halloween.
These things work for me, and they make pretty good money once they're up, but they are somewhat time consuming to get going, and I don't expect them to pay off immediately. But I'm not going after the quick and dirty - I'm in it for the long haul.
And from what I've seen - free content is worth just about what you pay for it.