How good are you with electrics? I had heaps of electronic ideas for my rs turbo which I never finished. to name a few (which I've started doing on the cossie now):

Electric sunroof conversion
Update window switches to illuminated versions
HID lights
convert all bulbs to LED (white not blue!)
Blue lit dash conversion
Dump valve in-car on and off switch
Hi / Low boost switch
Flamer kit
electric boot release
Fan override switch
police style flashing headlights
hazzard warning light "thank you" switch (how annoying is it trying to hit the hazard switch on the steering coloumn after someones let you out!)
interior door handle illumination lights (like the mondeos)
footwell and door courtesy lights (not cheesy blue!)