Robert Wilson, one of the most influential directors and performance artists of the past 25 years, has a website at http://www.robertwilson.com/ Visit his website and see what you can discover about the world of post-modern theatre.
This unofficial website of the Bread & Puppet Theatre http://www.pbpub.com/bread&puppet/bread.htm provides reviews of the B and P Theatre and insight into a unique form of modern theatre. Visit the website, read the reviews, then search for other forms of modern and post-modern performance and theatre that is pushing the boundaries of performance theory. To start you might try http://www.comm.unt.edu/histofperf/homepage.htm
To find out what is playing in the United States on Broadway, off-Broadway and at the major regional theatres, visit http://www.playbill.com/ Click on the "Listings" link and see how many of the productions are revivals of previous shows/ and which ones are totally new shows? Are there more revivals at regional theatres or do they feature recent productions? By visiting http://www.theatrela.org/nowgenre.html you can determine what is playing in Los Angeles.