My main idea I didn't end up working out was based on changeling wizard, whose 5th-level substitution feature lets you change your familiar into any other familiar as a full-round action. I didn't have any particularly interesting direction to take that, though.

Also, I toyed with the idea of entering Master of Flies early via Primary Contact so I could get 1/day Swarm Shape, but flavorful as it might be it was most certainly not particularly strong. Maaaybe I could've used the 'this is equivalent to wild shape' line to get Extra Wild Shape and get more uses that way, but I figured I needn't take the risk when I had better ideas.