The dancing curtains of the aurora are among nature's most enchanting and sublime events and are a beautiful demonstration of how our earth is protecting us from a hostile space environment. Information, sometimes current up to the minute and sometimes several days old, on real-time aurora status, solar geophysical information, and predictions are available at  Cary Oler's Solar Terrestrial Dispatch page . With the solar max coming up soon, there will be one or a few major episodes of aurora visible from the central and probably even southern latitudes in the United States.
You can find detailed info on all meteor showers and earth-relevant comets here.

Birds:
I love watching hawks and eagles and learned from Dave Fallow how to make a barred owl call. If you're in the Madison Wisconsin area or just passing through, by all means you should check out Dave Fallow's bird trips.There were great-horned owls nesting in the wingra woods section of the arboretum last spring and they may still be there.
Some useful mid-Atlantic links are Cape May Bird Observatory,  Hawk Mountain and  Blackwater National Wildlife Refuge

And if you can't get out to watch the birds, you can watch them from web cams.

Storms:
Storms are also part of the splendor of nature!

Wildlife camp:
I went to a terrific kids summer wildlife camp in West Virginia and it is still there! One of the counselors from when I was there 20 years ago is now running the show, so it must still be good! And now they have "adults weekend" in the middle of summer for those of us who never outgrew it!

Watch carefully:
The main thing with nature is to always be watchful and have patience. Look around you, the little things you wouldn't notice if you aren't paying attention.