One Word - Interior.
I had a heck of an idea earlier this year. It may involve taking a trip to a junk yard and finding interior panels I can remove from other cars like mine.
I've redone some of the interior, but I'm not nearly there yet. Last summer, I removed my dome light, ran the signal down to both doors via some gnarly looking conduit, and installed a handfull of super-bright white LEDs in both door panels. It's looking decidedly less normal and more spaceship-ish inside, but as I said, I've got a long way to go, and a lot of ideas to implement. Let me just say that perhaps the coolest one involves the ceiling.
I'm also working on a panel that fits over existing panels. It has pleanty of switches and glowy bits, but I'm going to have to keep it stowed unless it's a special occasion.
As always, I will be drawing inspiration from the Trilogy, and the original LucasArts PC Game "X-wing." I like elements of both, but I'm going to try to remain true to the films where I can. Well, except perhaps for that large unnecessary blue thing. (What was that supposed to be, anyhow?)
Thanks to the awesome people at the R2 Builder's Club, I have a perfect R2 dome, with a detail parts package. The dome is 1/16" Aluminum, so it ought to stand up to the elements. It will not be a permanent fixture. After much deliberation, I've decided to go with the kind of magnets that pizza boys have on their cars, to hold on the pizza boy designation sign. Removable is good, just in case the local P.D. wants to take issue with Distracting Ornamental Decor. Someone brought up a good point - if you ignore me here and decide to mess with your car's body anyway, make SURE you check out the local laws before you do anything drastic.
If you're curious about where to get parts yourself, check out this R2 D2 Builder's Club Member's page, but go there with IE.
Last summer, I spruced it up a bit for two reasons: The Maaco paint job was starting to flake in places, and I'd always meant to do the yellow bits. I have yet to take new pictures, though. [Bad Katie!]