Open Inkpot is a project with the goal of developing an open source firmware that will run on any eReader device. It uses a modified version of FBReader for the reading app. Currently supported devices include the Hanlin V3, Sony PRS-505, Bebook, Walkbook, Hanvon N516, and many others.
The new firmware is in early beta, so it might crash your eReader. It was designed for the Foxit eSlick, Orsio b731, Explay V3, and some of the other Netronix clones, but there’s no guarantee that it will work on your model. Use at your own risk.