The last 'toy' being installed is a FogMate unit which rings my own giant horn for me in case of fog or other needs. After that the only thing I can think of in electronics is upgrade the ICOM M600, get a pair of FRS radios, or maybe outdoor speakers for the music collection. Either that or a good spare set of headphones.
Funny how when you're almost done it's time to start repairs though ;D
Cheers
Michae