CNN Technology just published an interview with Philip Kaplan, the co-founder of Blippy, a new site where you enter your credit card information and every time you make a purchase, that information is published online in a Twitter-like fashion. Stephen Colbert recently mentioned the service on his show, including some blips from people who had spent money at Wendy's and Panda Express.
Kaplan mentions in the interview that it can be helpful for people to see the market value of things like gym memberships so that they can make smarter purchasing decisions. He also notes that it provides free advertising for the vendors your friends are purchasing from. On the other hand, the thoughts of tracking a person's credit card purchases and making them public is off-putting to some.
I'm actually tempted to try this maybe with just a credit card I only use for certain types of purchases or maybe with the Journyx card I buy everyone's flights with. If you look at Blippy's front page you may find that the data showing up there is more innocuous than one might think.
It is just a very weird world we are all walking into here, and Blippy is just yet another example.