via http://www.aep-emu.de/

lambnes is an open source NES emulator written in Java and is yet in a very early stage of development. A new version has been released.

Quote:
version 0.0.6 has been released. This release includes support for vram +32 incrementing and fixes some issues with the background color. Various games are kind of working now. Emulator speed is still a significant issue that needs to be addressed.

features:

working ppu

visualizations of palettes and pattern tables.

unimplemented:

apu