Seeking to increase support for the Museum of Contemporary Art of Georgia (MOCA GA) in Buckhead, the Atlanta-based foundation Possible Futures is offering a membership challenge grant. Through Nov. 30, Possible Futures will cover half the cost of annual MOCA GA memberships purchased by artists and students. Discounted memberships are $12.50 (good for free general admission and opening receptions). Details: www.mocaga.org. HOWARD POUSNER