I just committed the code that completes (functionally, at least) my JREFinder/Injector pair. The JREFinder checks a number of locations and installs any JREs it finds there. I recently added a polling mechanism to the underlying Discovery plug-in that makes it poll all such "found" JREs and notifies its clients when these JREs no longer exist. JREInjector is one such client, and when it gets the "unfind" event, it uninstalls the JRE that was unfound. Thus, when I run my Eclipse app, I can install multiple JREs and they're automatically add to the JRE Preferences list. Then, I can go and delete or rename the JREs and they're taken off the list...automatically!
For everyone who contributed the locations of their JRE installs, Thank you very very much.