Rant
NaNoGenMo 2015 is almost here. There’s a lot of resources for text generation available, but here’s one more that is fairly complete in itself.
Rant is a language for procedurally generating text, created by Nicholas Fleck. It’s got a lot of built-in support for various kinds of variation. Even if you don’t want to use it directly it’s got a lot of ideas to be inspired by, and the C# code is MIT-licensed.