The voice in the middle of 'One of These Days' is Nick Mason, and he says "One of these days I'm going to cut you into little pieces."
At about 3:00 or so, there's a faint organ riff that sounds a lot like the Dr. Who theme to a lot of people.
In the Westwood One broadcast of Waters' Quebec performance of Radio KAOS, a member of the audience asked Waters who it was he wanted to cut into little pieces. Apparently this brought back fond memories for Waters, who replied that it was an English disk jockey named Jimmy Young. The song was meant as a personal attack. The band used to play bits and pieces of Jimmy Young's radio show spliced together in a completely nonsensical manner, immediately before playing 'One of These Days.'