Prestige Classes and Favorite Monsters
Adventuring Scholar -- Not bad. Hit disc is d6, requirements are Knowledge or Lore (any) 5 ranks, Gather information 5 ranks, Profession (any appropriate) 5 ranks, Skill Focus (Lore or Knowledge skill). The "Against All Odds" ability that mimics their legendary luck is cool.
Bone Grinder -- Spellcasters who use magically prepared body parts to augment their spells. These are "spell enhancers" and are as cool as they are creepy.
Monster Hunter -- About what you'd expect.
My favorite monster is probably the Boatman. The descriptive text is wonderful and the mental image as you read it is pretty scary.
Second would be the deathjack. I've got a thing for big mechanical monstrosties.
(BTW -- Thanks for noticing the Construct Mechanus stuff. I'm having fun with it and have been getting feedback from the editor and a few trusted others who are playtesting and reading. Overall comment appears to be more but since I planned on doing a second book I'm not going to rush to expand this one.)