After setting aside $40 - $50 million for myself I would definitely pay for college for my nieces and nephew, tied to their continued good performance in school. I would set up scholarship funds for others and grants/stipends for talented but broke figure skaters. As a figure skater, I've got a huge soft spot for this. I have seen firsthand at least three very talented skaters that could not get to the national and world stage all because their families could not afford five figures a year to get them there or get sponsors to lighten the load.
With hundreds of millions, I'd have the dough to fund a medium sized construction company to build small and affordable homes and maybe some apartment communities that would provide a nice and safe place for working class folks to live, be proud to own, and be proud to be a part of the neighborhood. This action would create jobs locally as well fill a need for affordable housing. I would set up a rental management company that services (my) apartment communities and single family homes. I would continue donating money to feed the hungry and homeless as well.
I'd be able to create a community center in an at-risk neighborhood to provide a light in the storm for at-risk youth. It would provide free tutoring, supervised physical activities, and a grant for college if the kids stay out of trouble and maintain at least B average in school upon graduation from high school. This community center would have a stream of speakers who have "been there and done that" and would be able to encourage at-risk kids to remain on the right path.
As you see, I have lots of ideas but not 550 million. But I'm working on it and I'm smart enough to know the lotto not going to be the way for me, but there are other ways. Still, it's nice to dream :)