The second is the series of Monstrous Menaces does not disappoint. The author, James Mishler, provides interesting and unique characteristics for each monster that translates directly into actual game play. You get plenty of ecological information and tactical details that all add richness to the game without overworking the harried GM/DM/CK/Ref.
My personal favorite was the recasting of the goblin. There is a lot of great information here that is directly useful at the gaming table and will help distinguish the goblin from otherwise similar creatures, such as the orc and kobold.
The monsters are setting neutral--despite the detail provided, the GM/DM/CK/Ref will have a set of monsters that are usable in almost an campaign setting. And, despite the Castles & Crusades template, can fit right into any traditional fantasy role playing game with minimal work.