YAAB — Open Source Productivity App

This is a small custom brightness regulator app. The idea is to make screens of old devices like HTC Desire dimmer, as dim as possible. Of course HTC Sense on Desire has auto brightness feature, but average brightness level set by Sense is pretty much higher than needed for comfortable work. For people who use their devices for reading books, emails, texting, etc. this kind of application would allow to save up to 30% of battery. The website has a full explanation of the ideas behind the operation.