6,272 Post-It notes form a giant, editable "TO DO" on windows in Brooklyn’s DUMBO neighborhood. Passersby are invited to jot their own to-do lists on the notes. I love it. (Consider this "Solve Gordian knot of ever-increasing power & complexity in Photoshop; also buy new shoelaces," written in absentia.) More photos of the work are on Flickr.
In her Type the Sky project, Lisa Reinermann captures buildings that form letters against the sky, creating a photographic font. [Via]
For more big letters, see previous type entries filed under Enormousness.