There's a lot that can be said about LotFP Weird Fantasy. Some like the niches carved out for each class, some lament the lack of combat advancement for any class but fighters. In my eyes, the D6 skill system for Specialists is one of the best things it brought to the OSR, eclipsed only by the Referee Book.
I've spoken highly about the Ref Book in the past and was disappointed when it was not released as a free PDF when the core rules for WF Grindhouse were released to the masses. Disappointment no more.
The new printing of the LotFP Referee book is taking way longer than expected (surprise), so with no in-print Referee book the geniuses over at LotFP thought that maybe some sort of Ref information should be available. So here, free of charge, is the Referee book that was included in the Grindhouse set.
Keep in mind that LotFP is a living game and this PDF here is four years old. The next printing of the Ref book will be a complete rewrite and expansion (will be at least three times this size), new layout and graphic design, all new artwork, etc.The advice contained within the pages of the LotFP Weird Fantasy Referee Book is applicable to any OSR game. Heck, much of it fits well no matter what system you are running, OSR or not. Pick and choose what works for you.
The price is free. The reward itself is priceless.