Does anyone know of a good module I can purchase that could be used for a library.

I want something that can be searched via typing and category options. I want there to be an option to choose a category then search through that category for keywords. Right now all I can do is one or the other.

I'm looking for really good library search function, if it could search through pdfs that's better, if it is searchable on Google that's awesome too. I just want all these documents to come up accurately in a search. Right now I feel like you type in a word and all the documents show up in a different order, its not pretty.

Any suggestions would be awesome.