I took a little time to sort out the main details for an open source monitor for the openrevolt/cougar controllers and others. This one is cougar specific but there are other uses certainly.
The main strengths here are:
Open source, that what projects like opengauge.org and openrevolt are all about.
Java based so it is cross platform to its core, and not as an afterthought.
Cross platform without barriers means more people can use it.
Low CPU usage.
Should work on most any grade of computer, from 33mhz on up.
Fairly simple program that tinkerers should be able to grasp and modify for their own purposes.
USB or Serial interface is well tested. Currently I am using it with a USB interface via a serial emulator, from ftdi, but straight serial is trivial too.
Right now it just initializes the conversation with the cougar (sends it a "rtd-period 1000") and logs the data to comma separated values (so you can analyze them in your spreadsheet of choice) and graphs them on the screen.
The code (and arduino based "dummy" controller) are on the wiki:
Javamon - EcoModder
I have also written a java based programmer for loading hex files which should not be hard to integrate:
Arduino Forum - under 1k bootloader, any interest?
Heres a pic, just a proof of concept here really:
Also, I usually cheat and borrow rxtx from an arduino installation:
Arduino playground - Java
but the packaging could use some work too.