Looking for a PDF file? Try Data-Sheet. It’s a PDF search engine which is also powered by Google. What it does is filter the search results and only display PDF’s. This is a useful tool that you can use if you are specifically searching for PDF’s.
Instead of using Google for searching for Portable Documents, which gives too many results from websites containing the keyword “PDF”, you can probably find what you are looking for in Data-Sheet a lot more quickly. If the PDF file that you’re not looking for is not there, then your time will not be wasted checking out each and every Google search result.
The search engine is not that perfect. When I searched the term Googolopoly, it returned zero result. FYI: Googolopoly is the Google Monopoly board game distributed by Box.com and is available for download in the form of a PDF. So when it comes to being indexed by Data-Sheet, it is up to the uploader (owner) of the PDF to name the file properly, since I have not heard of a BOT that can crawl through PDF’s (yet). It would also be helpful if they can accept PDF registration from users and tag those files like they do on images for more efficient searches.
Given its limitations when it comes to properly returning results, Data-Sheet is also a handy tool to store in your bookmarks. It provides quick searches and they have a database of PDF’s available in their popular page for you to choose from and download.