Brute-force password cracker programs which claim GPU support include John the Ripper, ighashgpu, oclHashcat, and others. oclHashcat appears one of the more popular, but I am not sure which AMD/ATI GPUs it supports. (I have an ATI card.)

Which of the password cracker programs has the greatest ATI GPU support?

Which is the easiest to use as an API library?

Which is the most reliable?