Lune is an explorator of Lucene index. It is similar to Luke, yes it is a sort of NIH syndrome. But as a user I find the eclipse-ish UI a lot more user friendly, and as a developer the Eclipse framework is a lot more powerful than Thinlet, the framework Luke is based on. As it is based on Eclipse, it could be integrated to your development environment, Lune being a perspective. On the other way if Eclipse is not one of your environment, Lune is available as a standalone application (only the required part of Eclipse will be embedded).
Another feature I developed when I was looking deeply into Lucene internals: from a file that define the format of the index, a UI was generated to browse the index internal field by internal field. It worked once, but I didn’t touch to it again and then I removed it from the Lune UI since it is very experimental.