When I was doing my testing, I was breadboarding the bare chip with crystal, caps, and resistor. I didn't get past the blinking LED but I will.
I have not looked too closely at the Pro Mini since for a couple dollars more you can get a Nano with a USB to serial built on the board. It also breadboard quite nicely. I prefer the Nano to the Uno or Duemilanove because it fits so well on a small breadboard.