Google with default settings is useless and using more sophisticated queries quickly walls off the user with increasingly annoying captcha. The "world's knowledge under you fingertips" motto is still valid and brilliant though. My personal solution is library of OCR-ed PDFs with most established books from various domains, git repository for each domain. Greppable in miliseconds, locally. Hijack this, SEO experts!
Based on your reply to handsomechad, you may think that it's easiest for people to just build one themselves. But there may be a business opportunity in providing a pre-packaged solution for the masses. In the same way that Dropbox provided a tool that was "trivial" to experts, but was difficult for non-experts (see the infamous comment here: https://news.ycombinator.com/item?id=9224), if you have a tool that is essentially a rival to Google Books for reference texts, that is interesting.