An Erudite Madman in Erud's Crossing is a one-hour spawn. Always spawns in the same place, then starts wandering. Placeholder is An Island Madman. Drops various earrings of resistances that can sell for several thousand plat. Can be camped starting at level 15 or so (as a consequence it's pretty heavily sought-after these days).
http://wiki.project1999.com/An_erudite_madman