Frequently I am asked to provide information about the kind of people online. This is a great site for providing this kind of information:
http://www.pewinternet.org/Static-Pages/Trend-Data/Whos-Online.aspx
For example, I just read that 70% of people age 50-64 use the Internet. Additionally, 1/3 of seniors are using the Internet (senior defined as those over age 65).
So if your a data geek like myself, enjoy.
Cheers,
Drew