A secret I have for magic users is the rituals, working with the players to create items and objects. These are normally low level, have a risk to there creation, and are limited because of ritual rules. The fun thing about this is that you can design questionable spells for the players, like Healing Stone: This ritual is perfomed under the light of a full moon and places a number of wounds into a stone, for the recovery of points. The amount of wounds stored is of a creature killed in the ritual, note prey animals in the back of OWB. Casting is is 2xW+1 of creature (snake has W of 5, casting number is 11). Failure results in roll of 'blow to head' critical. Once points are depleted, stone is worthless.
But I also recommend:
http://www.blackindustries.com/pdf/w..._herbalism.pdf