nocache¹. It is LD_PRELOAD based so will only function within the normal limitations of that. It also comes with a couple of tools for examining and modifying a file's cache state, which makes it useful to judge its value in your environment.
One of my biggest use cases for it is with soxi, which I use solely for playlist manipulation. I don't alias my source tree search tools, because invariably I'm going to want all that stuff in the cache anyway for builds and such.