I am not quite such a serious person, so here are some other things which might be bought with the money.
28,000,000 decent restaurant meals at $25 each. Ten days of this is enough to take the whole country out to dinner.
3,600,000 of expensive sushi dinners at $200 each. Fortunately, not everyone likes sushi. One day is probably enough to cover everyone who'd appreciate a $200 sushi dinner, possibly several times.
Or 360,000 of wretched excess $2000 dinners with really good wine. Is there enough wine of sufficient quality to make this one work?
2,400 average houses at $300,000. The actual average is $264,000, but why not allow a little something for closing costs and moving and those unexpected repairs?
40,000,000 new hardcovers from Amazon, assuming that you also get a paperback or two for the free shipping.
Guessing at the numbers: 144,000 little business start-ups for $5000 each, 7,200 medium-small business start-ups at $100,000 each, or 360 large start-ups at $2,000,000 each.
7,200,000 hours of massage or a number of other professional services at $100/hour.
2,440,677.97 year-long subscriptions to the Oxford English Dictionary. That last person will have to throw in about $10 of their own.
720 X-prizes. This is the one that made me go "Gleep!". What research would *you* like to kick-start?
I think the $720,000,000 is just current operating costs. I get the impression it doesn't cover care for wounded Americans or wear and tear on equipment unless the equipment is replaced.