Almost every time I start to do anything creative I look around to see if a decent generator is available to help me out. I don't know why, but this is how I wound up writing and running a comic strip generator, which turned out to be about a kabillion times more work than just coping with putting clipart together in Photoshop. Lyrics are one area where I'm constantly looking into generators and tools and toys for some automated inspiration and am almost always disappointed. The Google searches have been the same for years, and even before that, the same group of DOS programs were kicking around the public domain BBS scene.
The best one I've ever used is Babble by Korenthal Associates in 1991. It's really almost perfect as far as I'm concerned. It allows you to load text files in and then mix them on the fly as you would audio on a mixing board, controlling the levels of the text files in the generated output and at the same time its overall coherence. It has logging, display speed control, even a whole bunch of goofy fun text effects if you want to make your generated text sound like Elmer Fudd dialogue.
The only problems are the limitations. You can only load four text files in at a time and they can't be very large. I'm not sure what the actual memory limit is, but one 100k file analyzed at high resolution won't even fit in memory. Twelve years ago that was an understandable limit, but I have a massive amount of memory on this machine and I'd like to use it to generate crazy nonsense, please.
But yet since 1991 nothing else interesting seems to have come along (on the PC at least). William S. Burroughs and David Bowie have both brought cut-up technique to reasonably mainstream attention and it seems like language nerds should have been all over this by now. I can't be the only person interested in this.