John Chow, blogger and Internet entrepreneur in Vancouver, British Columbia, is among a growing group of celebrities, bloggers and regular Internet users who are allowing advertisers to send commercial messages to their personal contacts on social networks. For the last month, he has used the services of Ad.ly, a start-up based in Los Angeles, and Izea, based in Orlando, Fla., to periodically surrender his Twitter stream to the likes of Charter Communications, the Make a Wish Foundation and an online seminar about working from home.
