The Cleveland Museum of Natural History's Frontiers of Astronomy series has a really good one for Thursday, April 11:
"For the last 14 billion years, our Universe has been expanding. This expansion has been governed by the opposing influences of dark matter and dark energy. Dr. Megan Donahue will explore the evidence for dark matter and dark energy, and the prospects for determining the exact nature of these mysterious substances."
These events are free an open to the public, and parking in the museum lot is free as well- but be sure to arrive early because these FOA lectures have been very well attended! The actual start of the program is 8pm.
See you there! :)