I didn't think it'd be that hard to find an iPhone-compatible car charger that has an aux-out from the charger (I don't want to have extra cables) and a built-in amp.

I can't find one in a single package. 

Bonus points: Don't want a mount (DQs LiquidAux). I like dumping my phone in my lap or in the cup holder (I'm weird).

Update: Guess I'm going to have buy it piecemeal. G pointed me to the SendStation MiniUSB LineOut:

Perfect! I also ordered a cigarette lighter USB charger... let's see how this works out!