For any place west of the Mississippi, Sunday May 20, 2012 is the Annular Solar Eclipse.
For the entire U.S., Tuesday June 5, 2012 is the last chance to see the Transit of Venus in our lifetimes!
The U.S. National Park Service has created a website just these events. Check it out! Many parks will have evening star gazing programs after these events as well, so make sure to visit the park's website for event information or go to the www.nightskyparks.org website for a national calendar of park events.
NASA also has some great websites for these stellar events:
NASA Night Sky Network
NASA, NPS and USFWS joint website Earth To Sky
NASA Sun Earth Day where you can catch a live viewing of the transit on June 5th and see their national calendar of events.
For all things related to the Transit of Venus click here.
Remember to protect your eyes with approved solar filters during these events. Both the Transit of Venus website and the NPS Annular Eclipse websites have how to view the sun safely information.