I haven't, but I have a friend who did (Equinox). He lost 6k before the "company" was legally slapped for fraud or something like that. Then they were banned from doing business in our city.
There is another one that was doing hugely well a few years ago. I got "propositioned" quite often, and didn't know why until I foudn out that it could be because I lived close to where their main regional office was located.
Finally, one of my erm co-workers is involved in a travel-agency one. He's a decent man who hasn't tried any gimmicky tricks, which I applaud him for. Istead, gave me the bottom line on the numbers and their internal documents. From the looks of it, very, very few people will make money off of it. This co-worker is out $500 at this point, and will continue to cost him $50 per month to maintain his web presence.