Well, I'm going to promote
my own editor (TuneToy) here, since I also believe in free (as in open) software.
Since I love to mess with my engine, and I like to understand what's going on inside, the same goes for my ECU (since, in modern cars, it's an integral part of the engine).
So that's why I became interested in pgmfi.org. Since I have a lot of experience with designing and writing software (started developing software about 17 years ago), I wanted to contribute back.
The PJRE project seemed interesting (because I like Java (NO, IT'S NOT SLOW
)), but was pretty much dead. At the time, I was experimenting with the Eclipse RCP (another great open source product), and decided to use that as a base for my own editor. Started a project on sourceforge.net ...
With the current code base, you can open, visualize (3d), and edit roms with it (just OBD1 for now, but support for OBD0/2/whatever is modelled in the base).. The GUI parts are pretty rough, but I think the base model is pretty solid.
Anyway, people who like to work on an OPEN rom editor are welcome to join the project. It's there, and you have the choice!