Some 17% of online American adults have used the internet to sell things. That amounts to approximately 25 million Americans.
In addition, internet traffic data show that visits to classified ad web sites has grown 80% in the past year.
Almost everything imaginable is currently for sale or has been for sale by individuals on various auction or classified ad sites. Tangible items like pink plastic Christmas trees, collectible coins, wedding dresses, automobiles, books, or CDs share web space with a myriad of intangibles including virtual weaponry and characters from online games (sold for real money) and services including everything from finding a French tutor, a personal trainer or someone to clean your aquarium.
Demographically, online sellers have an "early adopter" profile and they are relatively intense users of the internet.
http://www.pewinternet.org/PPF/r/169/report_display.asp
Report is available online in PDF format:
http://www.pewinternet.org/pdfs/PIP_SellingOnline_Nov05.pdf
