MUPEN64 is a n64 emulator designed to be multi-OS. On 2002-07-06, 0.0.4 is released for Windows, Linux and QNX.Now it has a gui, and can use all the zilmar specs gfx and input plugins. You can also select one of the three cpu cores from the gui. The pure interpreter core has the best compatibility but it's really slow. Check the README to know what's new.
QNX port was added on 2002-05-03 by Muad. You'll find in the archive all the changes he made to compile it, if you are interested.
More details can be found on their website at http://mupen64.emulation64.com/index.htm