The wealthiest are likely the same people who recognize how improved infrastructure will generate returns for their businesses or the country. So rather than waiting for congress to act on the Jobs Plan, this donation pool would efficiently identify where infrastructure would do the most good.
Next, recognize these heroes (Warren Buffet types) with a sign at the project site similar the Adopt a Highway program - that's smart marketing. In the case of multiple donations, make more signs or post the top 3 contributors - they will compete, so let them.
And for those who are feeling guilty about their wealth, this could be a channel for them to redeem themselves and be more accepted in society. Parade these folks on CNN Heroes.