I acquired an Android device, but haven't been too happy with any of the free PDF viewers I tried for ebook reading. E.g., some don't keep your place in the document when you exit. Anyway, the closest I found was the APV project, and it being open source, I joined and added most of the features I wanted. In case anybody else wants an acceptable and free PDF Viewer for Android, a pre-release version with a whole bunch of enhancements by me is here. Send me bug reports.