One of the best-known superfamilies is of course Luc(as) de Groot’s Thesis, currently including the following members:

– TheSans (Hair/Condensed)
– TheSansMono (SemiCondensed/Condensed/Typewriter)
– TheSansArabic
– TheMix (Condensed)
– TheMixMono
– TheMixArabic
– TheSerif
– TheAntiquaB/TheAntiquaSun

There’s a lot of potential for expansion, obviously. Can’t wait to see the release of TheAntiquaSun Mono SemiCondensed Hair.

Try these on for size: http://www.fontshop.com/fontlist/super_families/

Panoptica doesn’t have as many fonts as Trivia, but it equals the number of styles (seven), with a different plan:

Oldstyle (Regular & Italic)
Egyptian/Slab
Script
Octagonal
Doesburg
Pixel
Sans (Regular, Medium and Bold)