In March 2010, I developed "Carbon Footprint Calculator" using Visual Basic 6.0, which was the first application I ever created. The purpose of the application is to encourage people to protect the environment by reducing their carbon dioxide (CO2) emissions.
In 2010, the application won the second prize in "The Visual Basic Programming Contest in Hangzhou" (杭州市VB程序设计大赛). With this application, you can calculate the amount of carbon dioxide produced in your daily life, such as when taking planes or driving cars, and so on.
You can download the software from the link, but please note that the application is in Simplified Chinese.