Regal Entertainment Group is offering free movies on Tuesday and Wednesdays at 10am this summer.  This offer is available in over 550 movie theaters through out the United States.  My local theater has been offering this for years and I can tell you, arrive early.  It is first come, first serve and there is usually a line to get in.  Keep in mind that the movies are not new releases, but it is a great summer activity that is FREE! 
For more information visit their site Here and see if a theater near you is participating.