The Knight Arts Foundation is helping to produce 1,000 Random Acts of Culture - unexpected artistic performances out in the community. They're all documented at the Knight Arts website. I found out about them today when WCPE had a Facebook link to the Hallelujah Chorus:
The Opera Company of Philadelphia led 650 singers from 28 performing groups in this unexpected performance at Macy's in downtown Philadelphia.
Two of my other favorite performances from their website are the Tango in the Charlotte, NC Airport, and Opera at the Charlotte Belks (I particularly like the second opera performance which starts at 2:40).
I wish they did these in the Triangle!