Radiohead's Kid A, and "Idioteque" specifically, pushed the band decisively in its avantish, electronica-soundplay direction. What I didn't realize until recently (after following up a song blog comments from the Willens post earlier on Monday) that "Idioteque" was sample-based.
Part of the story is here on Paul Lansky's site. A sample from his composition, "Mild und Leise", based itself on a theme from Wagner's (in)famous Tristan chord, forms the harmonic center of Radiohead's song.
Mild und Leise - Paul Lansky