When creating a post have an option to donate x amount of the rewards to the Steem fund account to help support the blockchain. Make it public how much people donate. Give them badges for donating. Most people, especially in the public eye would feel uncomfortable not at least donating a tiny amount.
This would make all the difference in the world and raise a lot of money. Everyone is always claiming they want to help, this would be something every single steemian could do to help. And just keeping it real, the social pressure would be enough to get most people to contribute something.