WebNotes, a research tool developed by, and for, serious researchers, allows anyone to highlight and add sticky notes to web pages and have those notes instantly added to a web-based research file. For anyone flying through HTML pages like so much paper, it could be really handy.
At first glance, long-time Firefox users might recognise certain similarities to Scrapbook, an award-winning Firefox extension. The main competitive advantages WebNotes has against its predecessor is that it syncs everything to an online account rather than a local database, offers an easily exportable "report" of all your highlights and notes, and, in the paid "Pro" and "Group" solutions, offers annotation of PDFs that are uploaded and converted through WebNotes' site. The main difference, which is really a user preference, is that WebNotes operates through a (hide-able, optional) toolbar or a bookmarklet that works on all browsers, while Scrapbook, a dedicated Firefox project, pops out from a sidebar.
Signing up at WebNotes nets any new user a 14-day Pro account trial, which includes the PDF annotation powers, so students working on a big project should keep that little freebie offering in mind. WebNotes is free to use with a sign-up.