I got a seaweed body wrap years ago because I am sucker for anything that has to do with weight loss...
I think it lasted for over an hour and it was very relaxing! Did I lose weight? No, but my skin was smooth for a long time after, my stretchmarks were softer and my jeans felt a little bit loose too-but all this was temporary.
I remember it was quite messy and I think mine at the time cost $100. I hear since I have gone, they have come out with some really cool ones like the Infrared body wrap that is suppose to give all kinds of benefits like pain management, cellulite reduction, detoxification, and weight loss. I have read a lot about that one but have not tried it yet.