Native instruments have released a product called Abbey Road Drums:http://www.youtube.com/watch?v=f4JLz316ALw
Everyone knows that studio 2 at Abbey Road has a sound. These kind of products are becoming more popular where you have samples recorded in famous spaces.
So I seem to recall Frank mentioning releasing a sample library for other musicians to use.
I think there is quite a bit of commercial potential in this type of product.
I see Audioease have already sampled some aspects of the UMRK for their altiverb product:http://www.audioease.com/IR/VenuePages/umrk.html
So what about some of the following:
The Zappa Synclavier sample library series.
Modeling of Franks amps, FX and famous Guitars.
Modeled plugins of some of Frank custom gear.
Sample Library of instruments lifted from the multitracks of a selection of classic Zappa albums.
A nice sample of Frank's Piano.
The list goes on.