Billionaire inventor Gary Michelson is promising $25 million to the inventor of the first safe, non-surgical procedure to spay or neuter a pet. But that's not all. Michelson is also offering $50 million in grant money to explore plausible ideas.

I have to think inventors will be up to the challenge. $75 million is a lot of money. And non-surgical ways to spay/neuter could go a long way towards solving the pet overpopulation problem. Have an idea of your own? You can read more or look up the contest rules.