Myself, I think I'd go with some environmental charities first. Things I once belonged to and haven't donated to in a while. The Cousteau Society and the National Arbor Day Foundation come to mind. Some of the charities DNA supported very avidly during his (brief) life come to mind as well.
Then perhaps donations for medical research. American Lung Association comes to mind (being a lifelong asthmatic).
And then perhaps some technology donations. Fund some open source projects perhaps. Or help some kids get new computers in their schools, where they're needed.

And make sure I was living solo and comfortably, of course. :P