If the "Gay Cure" iphone app doesn't do it for you, then you might be interested in this new discovery scientists in China.

The scientists studied the effect of serotonin on the sexual preferences of male mice and found that mice bred to have brains unreceptive serotonin (a mood-regulating neurotransmitter) lost their previous impulse to mate with females:
When just a male was introduced into the cage, the modified males were far more likely to mount the male and emit a "mating call" normally given off when encountering females than unmodified males were. [...] However, a preference for females could be "restored" by injecting serotonin into the brain.
Let's just hope that they won't attempt to hunt for human candidates to conduct these tests...

via BBC