Accessories-wise, I'd love to see:
A pair of post-'hint' Starscream feet from TFTM. Maybe a crushed coronation crown as well.
A small version of the Revenge, scaled to fit with some of the smaller toys of the Ark and the Nemesis.
A tiny pair of Rodimus Prime and Headstrong figures for him to hold in his hands a la Nightmare Planet.
A small version of himself in his 3rd handgun-laser mode, capable of being held by himself and/or other MPs.
His home-(well, psychiatric-ward)-made gun from Webworld.
The Key to the Plasma Energy Chamber.
Translucent "Crazy-energy-bolts" attachments for his head.