I was just checking the FAQ, and I found a way to obtain early tarrasque wildshaping, or any other thing with a foolish amount of hit dice.
Now whip out the Errata for complete adventurer, and you'll find out that Nature's Warrior, Warshaper, Master of Many Forms all stack with druid for determining HD limits. In fact, I think Daggerspell Shaper might too, as does Arcane Hierophant (Races of the Wild). If you start with precocious apprentice, then grab some bloodlines, you end up with
Wizard1/druidx/Master of Many Forms1/Nature's Warrior 1/Warshaper1/Arcane Hierophant1/Strong Bloodline 3
Giving up 9th level (and possibly 8th level, haven't calculated yet, however, you can achieve the brokenness of this before level 10, giving you access to 16hd more wildshape than you're supposed to. Can you say Dire Polar Bear? Get an item of permanent Enhance Wild Shape (comes to be pretty expensive), and rock out with Battlebriar (although I can't recall if the levels stack for determining what forms you have access to). Go MoMF the rest of the way (I believe you can put all 10 levels in), and just rock the FUCK out with 36 HD dragons.
thoughts?
EDIT:
RIP supermount.
EDIT2: Wow, WotC allowed Warmage to become the new Most Broken Class Ever
TMIf a warmage (CAr 10) gains access to all the cleric
spells though the rainbow servant prestige class (CD 54),
does he really have all those spells to choose from each time
he casts a spell?
If a warmage takes ten levels of rainbow servant, he adds
all of the spells from the cleric spell list to his own spell list and
can choose from all of them when he casts spells.