I’m trying out a new website called Fuelly.com that is supposed to help track your car’s fuel economy. The way it works is after you sign up, you input a few basic details about about your vehicle. Then every time you fill up, you record how much gas you put in and how many miles you went since your last fillup.

Over time, you can get a good idea of what kind of mileage you’re actually averaging. You can also check out what kind of mileage other people are getting with their cars and befriend others on the site, though I don’t know what the purpose of being able to do that is.

Obviously it will take about a month or two to see how useful this site is, but I think it will be good to actually keep track of my fuel economy rather than just do think about it as I’m filling up. What this site doesn’t appear to have (or at least I haven’t found it if it does) is a way to track gas prices.

If you want to check out my profile, here it is, though there’s not much to look at yet as I haven’t filled the tank yet. If anyone else decides to try it, let me know what you think.

If you’re in to the whole social networking thing beyond blogging, Facebook and Twitter and have a mission to be green, there’s also MakeMeSustainable.com. It’s a social network where you can keep track of your efforts to be more sustainable, see how much your footprint is shrinking and find other green friends that live closeby. I signed up for Make Me Sustainable nearly a year ago, but haven’t found it engaging enough to keep using. Maybe you’ll get more out if it.