It was the Clif 2 mile challenge a while back that got me thinking. I rode for fun, not utility. But, the concept kept nagging at me.
It took me a while before I put the idea into practice, picking up more and more trips by bike....the dentist, the farmer's market, the grocery. And then I changed jobs and started commuting.
Now most days my car is a $25K helmet shelf. It goes for a drive every 2 or 3 weeks while my bikes get 200 miles/week (150ish utility miles and 50ish miles of fun). I'm in better shape that ever and stress is way down.
I love the idea of your challenge and applaud your starting this. A challenge would have been that kick that got me started sooner. That said, our Bike Fed is running a summer time challenge. The goal is 1 million utility miles during the summer months. While I participate, I'm already in the converted....that doesn't mean I don't look forward to see whether I won anything in each month's drawings
For ideas ( http://www.endomondo.com/campaign/wi# ) [Note: endomondo is a *terrible* site, but the idea is sound]
2009 Waterford RS-14 S&S Couplers - Brooks B68-Anatomica - Traveller
2008 Waterford RS-33 - Brooks B68-Anatomica - Go Fast
2012 Waterford Commuter - Brooks B68-Anatomica - 3.5-Season/Commuter
2011 Surly Troll - Brooks B68 Imperial - Snow Beast