We all know and love Arcane Spellsurge. Allowing you to cast potentially twice the amount of spells per round, this spell is a stable of any sorcerer build. It's not quite as powerful in Wizard builds, because it's a bit more difficult for wizards to make standard action spells into a full-round action, but it's still useful for freeing up the standard action for something else. Casting as a swift action is still useful.
If only there were some way for us to get more than one swift action per turn.
We all know and love Ruby Knight Vindicator. Allowing you to get an almost unlimited amount of actions per turn, this class is a staple of any crusader/cleric build, heck, many clerics dip crusader just for this class. It's not as good for primary casters, because their spells are usually standard actions, but it's still useful for spamming swift action spells.
If only there were some way for us to cast standard action spells as a swift action.
Now, you obviously see where I'm going with this. But! Arcane spellsurge speeds up arcane spells, and RKV pretty explicitly advances divine casting. WAT DO?
Enter the Sha'Ir. This class from Dragon Compendium is awesome for all sorts of reasons, but most importantly it can cast both arcane and divine spells.
You can either dip crusader, if you don't mind one more lost spellcasting level, or pick up Martial Study/Stance. You can get functional turn undead by taking the Planar Touchstone: Catalogues of Enlightenment feat, choosing a domain like Air or Scalykind.
So there you have it. Arcane Spellsurge + Divine Impetus via Sha'ir = Number of spells per round limited only by number of spell slots and nightsticks.