Seen on Facebook: Ensemble, a memory tool for larps:
Yes, its basicly a character database, with an option to print a nice little booklet or flashcards. And it costs money, which only high-budget games can afford. But its interesting that they think that people fumbling to remember names and relationships is a big enough problem that GMs would be interested in this (and that players would be motivated enough to do their pre-larp homework to remember it all).