This is a complete compressed (.zip) file containing screenshot references of all the JK2 and JKA model assets, located in the base/models/map_objects folder. This should make it easier for modders of the game to browse the models and decide which to use without manually loading each and every model in Radiant to check. You should unzip the entire library to your computer so you can utilise your OS's inbuilt thumbnail viewer.
Awesome idea!