I wrapped the libmobi library into an IFilter shell extension. It allows windows desktop search to access the text of AZW/MOBI e-books for fast indexed keyword searches. Here is the free installer to download:
http://zabkat.com/blog/ebook-kindle-...ows-search.htm
note that encrypted AZW books cannot be accessed at present. I'm not sure if that's possible outside the "owning" kindle device