i found a couple HTML5 audio examples:
jQuery plugin:
http://www.happyworm.com/jquery/jplayer/latest/demo-01.htm
This site uses the above jQuery plugin for a stream:
http://wfmu.org/html5/player.php
This one uses streams from scratch:
http://www.trygve-lie.com/blog/entry/html_5_audio_element_and
Another tutorial:
http://html5doctor.com/native-audio-in-the-browser/
As long as the stream has Ogg Vorbis source and MP3, it should be good.
How could I use JavaScript to create a channel-picker that would use a different source for the audio stream upon changing the channel?
You should be able to simply use jquery or regular javascript to remove the old tag from the dom, and create a new tag, set the source to the new mp3 file (from your track listing selector), and start it playing.
i.e.
Some pretty decent examples here