1)   Book Search Pro 2.0
This is an easy-to-use search tool. It allows you to search thousands of PDF, DOC, PPT, RTF, XLS files from internet. It's as easy as you're googling. You just type keywords and hit enter, then you will get thousands of results instantly.

 2)   Instant Document Search 1.12
Very fast document search engine for your computer or local network. Support of MS Office files, WordPerfect, PDF, web pages, plain text files and other documents. Instant Document Search is easy to use, but powerful tool.

 3)   Openfind Enterprise Search 2.0.11
Openfind Enterprise Search (OES) is designed for easy installation and simple configuration, allows setting up intranet document search and Internet website search in minutes. OES free edition allows 2 indices and up to 10,000 documents per index.