I also have some homebrew to this effect. Here, take a look.
The Rearranger, a transmutation-based caster.

The Savant and Summoner, a pair of specialist casters (Savant was Abjuration/Divination and Summoner was summoning focused Conjuration). That link also has the Spellweaver, which wasn't actually a focused caster, just a strange gishy class I never completely finished.