My picks off the top of my head are:

- Chevrolet SSR
Limited production, truck/roadster, especially 2005-2006 w/6.0 V8.

- 2004-2006 Pontiac GTO
The epitome of a flop, but great performance. Again, especially 2005-2006 w/400 HP.

- Chrysler Crossfire, especially SRT6 models.
Too many things about it for it not to be a collectible.

- Acura NSX
The most expensive Japanese car ever (at it's inception), great performance/handling/reliability. Plenty of mods available, so stock ones will command a price in the future.

- Twin Turbo Supras already mentioned in previous post.

- Last gen Mazda RX7 Turbos.

- Solstice GXP/Sky Red Line - depending on how many they make and for how many years they are produced. I doubt they will be nearly as collectible as the Crossfires though.

- Mid 1990s Buick Roadmaster Wagon. The last of the Woodys. Having an LT1 doesn't hurt either. I would own one today if my wife would let me.

- Audi TT Quattro Roadsters - not for sure, but a good possibility.

- Honda s2000 - not for sure, but a good possibility.

- Prowlers.

- Subaru WRX STi.

- Corvette Z06, especially C6 models.

- Ram SRT10.

- Basically all SRT cars - 300 SRT8, Magnum SRT8, Charger SRT8, maybe SRT4.

Only time will tell I guess.
I know before I bought the SRT6, I spent almost a year researching and projecting what would be collectible in the future. Of course I could be an idiot and would have been better off buying a Chevrolet Aveo!