Some of the nicest exhibition invites are produced by The Fraenkel Gallery in San Francisco. They also represent an impressive roster of photographers so they have great images to work with. Beyond that, they seem to go one extra step in the design and production of their invitations such that they become little works of art in their own right.
The image above was taken by James Danzinger (and borrowed from his blog, "The Year in Pictures") while visiting the Fraenkel Gallery in 2009; it shows a wall in the office with framed (apparently never folded) copies of some of the invites. And what follows are more examples.
Diane Arbus, 2007
8 by 10 inches, unfolds twice to a 16 x 20 inch stiff sheet
8 by 10 inches, unfolds twice to a 16 x 20 inch stiff sheet
Katy Grannan, 2006
8 by 10 inches, unfolds twice to a 16 x 20 inch stiff sheet
8 by 10 inches, unfolds twice to a 16 x 20 inch stiff sheet
Group show, 2009
8 by 10 inches, opens to a 16 x 10 inch stiff sheet
8 by 10 inches, opens to a 16 x 10 inch stiff sheet
Bernd & Hilla Becher, 2009
8 by 10 inches, unfolds twice to a 16 x 20 inch stiff sheet
8 by 10 inches, unfolds twice to a 16 x 20 inch stiff sheet