They are specialists that improve the rate at which some things improve, most notably the armsmaster, who makes your weapon skill increase more quickly. Some items, (the "foresight" is one, I think) contain them at max power, so it's kinda cheating to use them. Contrary to what some may believe, it doesn't take much longer to collect them fairly. I beat the Uber Prinny and Item God 2 without any cheating, and it took only a few days of specialist collecting. Statistician, manager, and banker(?) are the other three. They increase experience gain, mana per kill, and money (hell, whatever) per battle, respectively. They cap at level 300 or 450 for the armsmaster (might want to double check that), so the level 99,000 ones that come from glitched items aren't as great as they seem. Plus the item world is fun and you get all the other great specialists while gathering those guys if you do it the way you're supposed to.