Master Cleanse Diet
The Master Cleanse (also called the Lemonade diet) came into popularity during the 70's. The basic idea is to drink nothing but lemon juice, with a few other ingredients, for two weeks. No food, nothing else to drink but water, for TWO WEEKS!

Basics:

The Master Cleanse is supposed to be used as a detoxification program--not quick weight loss.
Combine water, lemon juice, cayenne pepper and pure maple syrup in specific amounts and drink throughout the day.

Pros:
Those who have actually gone through with the entire 2 weeks tell horror stories about expelling a tar-like substance from their body--what they believe to be their bodies' toxins.
A lack of appetite follows after a few days.
Although it's not a diet, pounds fall off quickly. The author of Master Cleanse, Stanley Burroughs, admits the weight will come back just as quickly when the cleanse is over--like he said, it's not for weight loss.

Cons:
Uh, I think it's obvious--you can't eat for two weeks! Your body needs food and nourishment.

My take:
I actually tried this cleanse and lasted for about three days. I found the drink to be disgusting, it was a spicy lemonade and I don't like the taste of cayenne pepper. I have a friend who completed all two weeks, lost fifteen pounds but then quickly regained them. I think there has to be a better way to detox--maybe with fiber from veggies and plenty of water.