Sibelius: Symphony No. 3 [YouTube]. There is no imagery and no drama—except that of the musical events themselves—for you to lose yourself in. This is like Haydn. You can't do anything with it except listen to it.
Pluto, the Renewer is a short orchestral piece by English composer Colin Matthews, commissioned by the Hallé Orchestra as an addition to Gustav Holst's suite, The Planets. Program notes by the composer. Matthews commented on the piece, and Pluto's place, in an NPR interview a few years ago. The BBC's Discovering Music gives a good discussion of Holst's original suite (which you can listen to here).
A Sunday morning is a fine time to listen to Leonard Bernstein discuss Brahms' 4th symphony, complete with crackling vinyl noise.
If you have some time that needs to be filled with music, you might want to listen to all the symphonies of Shostakovich and perhaps all of Bruckner's as well - Bernard Haitink's recordings of these two cycles are available for listening on myspace (of all places).
Imagine this: 'This evening we are going to hear the 2nd Symphony by Claude Debussy, the Austrian première of Insect Life by the Finnish opera composer Kalevi Aho, and the 2nd Symphony by Bela Bartók.’ What is a symphony? What does the concept mean nowadays? And what does it mean, to compose symphonically?
Course materials and taped lectures (nearly 70 hours worth) from John Ronsheim's classes on 20th century music at Antioch College.
Playing with Dictators - an editorial on the New York Philharmonic's decision to play a concert in North Korea. One musician's account of the performance.
Interesting discussion on classical and pop music, and two related older articles on the Pulitzer nomination process from Greg Sandow.
The six string quartets of Béla Bartók: A guide for performers and listeners, by the Emerson Quartet...
Austria's AEIOU has bar-by-bar analyses of major classical works (of composers associated with Austria): audio, annotations, scores, and performance/score animations in various video formats, together with biographical essays on the composers. Some possible points of departure: 1, 2, 3.
Arnold Schönberg Web Radio - a rotating program of documentaries, lectures, history, the composer's own words, and recordings of nearly all his works. The Schönberg center also has some beautiful manuscript pages scanned.
The Unheard Beethoven - This website endeavors to make all of Beethoven's unrecorded music readily accessible to the public. These never-before-heard works are now available to anyone with a computer, a modem and a soundcard, in the form of MIDI files. At present, over twelve hours of Beethoven's music is available on this website and in no other listenable format.