Online money making schemes

Lately, I've been trying to find out money making opportunities online. The only criterion of such an opportunity has to be that it is free to join and no investment is needed on my part. I've found many of them - some ask to sign-up for a course, some ask to send them some money to begin online business with them. Some are free to join and if possible, to make some money too. I will list some of the opportunities that I found interesting and easy to sign up and start up.
-- If one has a high traffic website then putting ads and earning money per click is the obvious way to go. Google Adsense, Yahoo Overture, MSN adcenter, BidVertiser, and Adbrite are a few of the more popular online advertising businesses which are easy to sign up and get started.
-- Then there are multi level marketing business opportunities online. Recently, I found an interesting one called Best Cash Rewards where one can sign up within minutes. It doesn't require any investment. One has to just watch a seminar of about 30 minutes a week, and refer other people to this programme. That's all one has to do. The more people you refer to this programme and the more people they refer in turn, the more you get. The companies giving seminar get a captive audience for half an hour. That is what they want and they are happy to pay on per person basis who attend the seminar. One can sign up for this programme by going to this page.