Here are a couple of Internet demographics reports from the Pew Internet and American Life Project. It's specific to the US, but we all know the different filters to run this through for our countries by now.
I think their most recent study indicated that the average Inet user was a 45-year-old female, using it for the purpose of staying socially connected. That came out in the Spring of this year, can't find it on the site though. It was reported on Romenesko.