CEJavaComm - A driver implementation for the Java Communications API for the WindowsCE/Pocket PC architecture. This driver supports RS232 (serial) ports (and possibly IRCOM but untested). - http://www.teilo.net/software/CEJavaComm/
Java API for FireWire - A Java API for controling 1394 Digital Cameras (based on libdc1394 library). [Open source, LGPL] - http://jlibdc1394.sourceforge.net/
RCXComm - Java package for communicating with the Lego Mindstorms RCX Brick. The core of the RCX Brick is a Hitachi H8 processor that can be controlled in a variety of ways to read sensors, activate motors and do general processing. [Open Source, GPL] - http://www.iau.dtu.dk/~lego/lego3/rcxcomm/