Tauric, Symbiotic, Lycanthropy, Entomanothropy, and Petitioner uber cheese.
#1-4 allow infinite templates at +1-3 LA total, and #5 reduces the added creature's HD to 2 for a much lower ECL for #1-4, for a total ECL of 3, 4, or 5.
this gives you infinite stats, near-infinite special abilities, infinite feats, multiple actions per round, and lots of spellcasting.
minor trick- Chain, Repeat, or Twin Spell potions from a Master Alchemists allows you to 'cast' any level permanent spells on many creatures and objects for CHEAP!
There's probably even a way to do this w Epic Spells using some other spell reduced cheese