NPR “Xeni Tech”: Jigsaw wants your data: This is a tricky little service that makes Plaxo look almost legit. If you upload someone’s contact information, you can search for and download someone else’s. So anyone who gives you a business card is currency for you to use to get someone else’s contact information.
Members pay $25/month to obtain 25 contacts from the site, or agree to put in 25 contacts a month to get 25 others out. Users maintain the data, but unlike Wikipedia, they don’t do it for love here — they do it to score points, so they can download more contacts.