Qiqqa is a software tool designed for academics. Student, undergrads, postgrads, or other researchers... if you deal with a lot of PDFs or ideas, you'll love Qiqqa.
I've used this extensively over the past two years, and I can't imagine doing research without it now.
"Import all your PDFs and they're OCRed, tags auto-extracted, and Qiqqa helps you quickly populate any missing metadata. You'll love the full-text search, duplicate paper detection, and much more."
"Top-notch built-in PDF reader with annotating and highlighting, automated jump links, tablet sync, and so much more."
"Printable annotation summary reports for revision, and create mindmaps of your thoughts."
"Qiqqa connects to Word™ to make citing and bibliographies a breeze."
My favorite features are the bibliography generator and the powerful search engine. Highly recommended, and definitely worth getting the $36/yr premium version, if for nothing else than to help ensure that such a fine product continues.