Time magazine has an interesting article called "Who's Really Participating in Web 2.0" which gives some intersting facts and statistics about who is uploading on the web with information on the sex and age of those uploading the most. Even though more people are blogging and uploading and so forth than ever before it is still a small percentage compared to those that are considered "passive visits." For example, of all the visits to youtube only .5% of those visits are for uploading. Another interesting fact is that of those people actually uploading about 76% of them are male while the actual visitors to the site are 50% male and 50% female. In addition to the gap between the sexes of who is uploading and who is just visiting, there is a gap between generations in who is uploading. For example, 42% of the peple that visit Wikipedia are under 35 while 82% of those adding to the site are over 35. Anyway for more info check out the article those are just some examples.

http://www.time.com/time/business/article/0,8599,1614751,00.html