Are you using greenline web apps? I was thinking about this blending of words yesterday when trying to imagine a web app in physical terms. For example with our web based speech-enabling apps you can “carry” the sound files we generate from online text instead of printing a web page to read it while you are commuting to work for example. That makes us a carbon footprint efficient service. Another angle is the impact of desktop apps vs web apps on your computer. With web apps like ours, you are using less resources on your own computer and possibly extending the length of time that you will use it thereby also contributing to a better carbon footprint result. This is particularly important for low-end computers for example. Microsoft Reasearch has come up with a Joulemeter which is a software based mechanism to measure the energy usage of virtual machines (VMs), servers, desktops, laptops, and even individual softwares running on a computer.