I found a place where the first (and only!) free online version can still be downloaded.
Direct link to software: http://elgitar.com/downloads/FretBoardKnowledge_setup.zip
Also, someone created a video for that version, explaining how he created images of chordal inversions with the application. Note: This is not a core feature of the program, but more like a work-around. Still, nice to find this.