Bikes & Cars...

Send FuelFrog the miles you traveled on your last tank of gas, the price you paid, and the number of gallons of your next fill-up, and it will track your mileage. Once you've signed up for the service, it can keep tabs on your miles per gallon and how much you spend on gas. (Though maybe you don't even want to know these days.)

FuelFrog works best with Twitter, especially if you can tweet, as they say, from your phone right at the gas station. You punch in the numbers in order -- miles, then price, then gallons -- and send Twitter the text message. It works from your computer, too, if you don't want to mess with the SMS.

If you're tooling around town in a biodiesel or E85 vehicle, or are thinking about doing so in the neare future, the Seattle Post-Intelligencer has put together this comparison chart to clear some of the noise from the biofuel debate.

The chart starts with the source of the fuel, like corn and soybeans, and the kind of fuel these sources are made into. Then it digs into greenhouse gas emissions, resource usage during production, percentage of land needed to meet half of the demand for fuel in the U.S., and the pros and cons of each.

By breaking it down into a color-coded chart, the P.-I. has made it easier to know what all the fuss is about and have an intelligent discussion over organic coffees at the local bike-friendly cafe. (Every neighborhood should have at least one.)