Looking for a spreadsheet that'll help you calculate P&L? How about an earnings report for a publicly traded company? The Web is chock full of documents like these, but finding them isn't always easy.
Savvy Google users know how to filter Google searches by document type. For example, if you append "filetype:PDF" to your search word or phrase, Google will serve up PDFs that match.
But if you're a Firefox user, there's an even better solution: OutWit Docs, a Firefox extension designed expressly for finding documents.
Once installed, OutWit Docs adds an icon to your Firefox toolbar. Click it to launch the OD window, where you can enter your search term (and choose your desired search engine, Google or otherwise). The results are displayed in a list or icon view:
Cooler still, OD can find all the linked documents from any given page -- great if you want to plumb the depths of, say, a company site without manually clicking around.
Though technically a beta, OutWit Docs is an insanely useful plug-in that I think qualifies as the best document-search tool I've seen to date.