FYI on the OpenSource side of things, you can very easily create an OpenSource Filemaker project, the source code is freely distributed/updatable, etc. What you cannot distribute is Filemaker itself. Anyone who wants to monkey with the source would have to purchase Filemaker to do so.
I too am a professional programmer by trade (www.wasatchdev.com) and would love to help on a project like this, but sadly, I have zero Filemaker experience and as such don't own Filemaker either. Also, my RM interest is in RM2/RMC and an RMSS application wouldn't find much use in my limited gaming time.
Sorry to hear about John,
-shnar