I mentioned several potential classes in the X Without Spells post, but decided the one I wanted to do next was the Conjurer.
Concept: Goetic magician summoning (creating?) and binding creatures to perform tasks. Think: sorcerers in the Elric stories or the stories of Lovecraft and CAS, wizards in The Master of Five Magics and its sequels (by Lyndon Hardy.)
Alignment: Neutral or Chaotic predominate. Conjuring violates the natural order, but a Lawful Conjurer who only binds and banishes rogue conjured beings is possible.
XP/HD: As pre-Greyhawk Magic-User; Int is prime ability. They can use mundane or magical daggers and any staff a Magic-User could use.
Spells: None by default. Can research any conjuration spells, but spells known can't be "memorized", only written as scrolls. These require ink mixed with the fresh blood of a creature with HD equal to the spell level. If the scroll summons a specific creature, it also requires the blood or other body part of that creature, or of multiple creatures that approximate the desired creature (for example, lion's blood and an eagle feather to summon a gryphon.)
Other Abilities: Command Summoned or Conjured being as a Cleric would Turn Undead. Minimum effective HD of target is 1. The command can either be a single service (binding) or an order to depart (banishing.) If the Conjurer's level is 3 higher than the creature's HD, the Conjurer can make a pact instead for extended service; treat this as a henchman. A summoned being bound by a pact has a Loyalty score to the pact, not the Conjurer; its loyalty to the Conjurer is assumed to be the lowest possible.
Conjuration itself always requires at least a one-day ritual, which involves burning the ingredients described for scrolls in a brazier or other ritual object. On an unmodified roll of 2 (or the lowest possible roll, if using something other than the 2d6 Turn Undead roll,) something goes wrong with the conjuration; if the modified roll was unsuccessful, the summoned being attacks immediately and cannot be bound by that Conjurer; otherwise, the conjuration works normally, but a random unexpected creature is conjured instead.
Conjured beings normally vanish at the end of their service, returning whence they came. On a 5+ on a 1d6 roll, the creature doesn't vanish, but physically departs, looking for a new home in the Conjurer's world.