Also... on the other end of the spectrum, there is Sleepbot Environmental Broadcast [0] with Ambience for the Masses [1] catalogue of ambient music.

And... yes... Mixing of Particulate Solids radio (mops-radio.org - not in operation) will be missed with sorrow. It was a radio from two guys from Bratislava/Slovakia with three streams with only few slots... exceptional. Only recently they stopped streaming completely...

[0] http://www.sleepbot.com/ambience/broadcast/

[1] http://www.sleepbot.com/ambience/