[patio11]

Thats a hard question, with that kind of money I can't think of any obvious ideas that would have a big impact on humanity.

Hypothetically supposing you were to automate a labor-intensive process in the field of your choice, and market that successfully to 100,000 people saving them each one hour a year, you'd have contributed essentially fifty full-time workers of your chosen profession to the community. Those could be nurses or teachers or priests or what have you.

That is very doable on dollar amounts much, much smaller than $20 million. Plus, the Internet chews up numbers like 100,000 for breakfast.