Cherry Coke Zero!! That's AWESOME stuff right there! So is Diet Dr Pepper and Diet Pepsi Jazz Caramel Creme. I want to try the Diet Cherry Chocolate Dr Pepper though I haven't yet... the cherry vanilla one was pretty good.
I've never had Diet Mr Pibb... I didn't even know it existed...
Another recommendation: Diet Mountain Dew. That "tuned up taste" is quite an improvement.