In the ultimate combination of the "everyone knows where I am-ness" of Twitter and everyone's favorite topics, gas prices and fuel economy, Fuelly has just launched to help you manage the ins and outs of your gas tank.
The streamlined application lets you create an account and track how much you're spending on gas, how good your m.p.g. rating is — and compare yourself with other users. The site works a trick on an iPhone, letting you track right from the pump, and it has handy tips to conserve fuel without changing much at all. Like if you're idling for more than 10 seconds (ahem, drive-thru), it's better to park and hit the counter.