All they have is Atari stuff right now, but it is an interesting idea. All the games apparently work with MAME and they look pretty reasonably priced.
Each game costs around 8-24 credits with credits available for:
40 Download Credits $10.00 ($0.25 each)
80 Download Credits $20.00 ($0.25 each)
200 Download Credits $35.00 ($0.175 each)
400 Download Credits $60.00 ($0.15 each)
800 Download Credits $99.00 ($0.12375 each)
