A TwitterGram has a title and a small MP3 file. The title explains the gram, it must be no longer than 75 characters, to allow room for the URL of the MP3, which is about 50 characters.
Excellent video and audio mashup of George Bush and the U2 hit, "Sudnday, Bloody Sunday." The site features quicktime, but you can currently download a wmv version here: http://www.2nd1.net/uploads/bloodybushday.wmv and if neither of those work for you, s