Not particularly spell related, but still undead-happy:
Boats. Yah, yeah, most undead are too stupid to really sail a ship. So screw sails, row that puppy! Skeletons and zombies are bright enough to follow drum instructions and a warship with three decks of rowers that never tire make *excellent* time.
mining. Again, not so good at the knowing when to stop digging before causing a cave in. *BUT* they work tireless at simple pumps (archimedes' screw) to keep mines dry, don't use air, and you can always have a half-dozen of them working a drill crank as an undead auger.
Mounts. Why does everyone forget the zombie and skeletal horses? Sure, they're slow but load those puppies down! You can save a ton of cash by not feeding draft animals and undead don't suffer exhaustion.
Oh and a nice trick for pale masters is to act like a flesh golem. Once you get the arm and the body armor it doesn't take a whole lot. Have your apprentice take the role of the master and fade into the background.