A relatively tame/easy thing to do would be to simply boost article or youtube views, you could even charge a service. Boosting your views for articles on some sites can help generate much more genuine traffic by getting your article on the most viewed page, which usually results in a better PR and SERP result as well. You could also simply boost another site to boost the alexa rank.
One way should be pretty obvious to you but talk about it is banned on here and you have to know what you are doing if your gonna do it so read up well first.
Exactly what has been said here, boost views or sell the traffic. These are your 2 choices that I can think of. Both can be pretty profitable if you have multiple traffic sources putting out that much traffic.