This is the sort of thing that fans everywhere can get on board with. Maybe you cannot be there, maybe you cannot give a donation, but there's still a lot that you can do to help out.
One thing in particular that will really help spread the word online is the use of art and video. So I'm looking for vidders and fan artists. Whatever kind of artistic creation you want to make is wonderful.
I've checked with HFA and they say you are welcome to even incorporate any of the artists works into your work as long as it is kept online and as long as the art is used to advertise the event. They would really love if you can incorporate the event logo into the piece, though! There is also the Autism Speaks logo, too.
I would really, really love to see some fan videos come out, but please do what you're good at. When you've made the art, please post it here, and feel free to spread the word about it on your Twitter, blog, YT account, MySpace, Facebook, anywhere that you interact with people.
Let's try to get all of the Heroes fans involved in this as we possibly can! :D