The ‘Tokyo’ ident from Channel 4 in the UK.
These rolled out many years ago while I was living in England, but still stand the test of time as unique ways to portray the number ’4′. The channel did a whole series of these in different situations. The camera would glide around a scene and at a certain point the number ’4′ would reveal itself when the camera was in the exact right position to catch the perspective.
It was abstract, but it worked. The music composed for these also added to an air of intrigue.
Here’s a low-res compilation of some of the others: youtube.com/watch?v=-CVdllN67OQ