2. GreenCard

Along similar lines, why spend money on business cards that just get lost in the shuffle when you could use a digital alternative? That's just what Haploid's is for. Compatible with iPhone, iPod touch (2nd generation), iPod touch (3rd generation), iPod touch (4th generation) and iPad, the free app lets you create a business card on your mobile device and then share it directly with your contacts. The app is sold on iTunes, but I'm hoping Android is in Haploid's plans for the not-too-distant future.

3. Green Mileage

For those of us on the Android side of the fence, the free app is on hand to help us track our mileage as we go about the driving part of our daily business. Knowing your current habits, after all, is a critical first step on the way to cutting back and saving.

4. Fuel Saver