To commemorate the Rite centennial, the most effective and beautiful music animation I've seen
Visualizing music: animations can help us hear better

Postcard pieces

The London Sinfonietta had a composition contest recently, except that each piece had to fit on the back of a postcard.  Seriously.  And the results are are fantastic.  From their blog:

On Sunday, 15 September, the London Sinfonietta will be performing a selection of composer James Tenney’s Postal Pieces as part of Kings Place Festival.

Inspired by Tenney’s innovative work, we held an open call asking for compositions written on the back of a postcard and the response was phenomenal. A total of 355 RSVP compositions from 170 composers were sent in from 20 countries on 5 continents.
Also be sure to check out the brochure for their new season.  So much good programming and terrific, innovative presentation modes.  "This is not a museum" indeed.