(3.5) Metamagic Applied to High-Level Spells?

[avr]

Recaster (Races of Eberron) is all about metamagic, too. Besides the obvious class features you can also use the 2 spells you get to pick from other class lists for versions of spells which happen to be lower level on that other classes' lists.

Edit; Also, Jade Phoenix Mage (ToB) lets you empower or quicken spells for free after a successful strike.