If you use Diigo but are researching a certain topic for a book or term paper and also use Evernote, I recommend setting up an ifttt.com recipe similar to this one I'm using for my collaborative writing book. Everything tagged "collaborative writing" goes automatically to my collaborative writing book.
You could use this for a course. You could take everything on Diigo tagged with the course number into a notebook (or into a Google spreadsheet, for that matter.) There are many other sources of information you can use to collect information on a topic in one place.
We have talked before about the study benefits of re-writing notes - you READ them more carefully and you SEE them again as you write them, (AND you end up with more readable, neat notes in the proper format!)
Additional benefits of typing (digitizing) the notes:
Ability to add screenshots to embellish the material
Ability to use formatting to embellish the material
term.ly is the companion website for the terminology app for the ipad/ iphone. You can also shorten and share definitions. The main problem I had is if you use a diigo box, the search box tries to take over the words. Nice clean dictionary.
Multimedia online note taking tool. Students can capture screen images, make audio recordings for notes, or write text notes to accompany drawings. These different media can then be organized into videos!
I envision it being similar to Evernote with more interaction capabilities and with the great addition of being able to create videos of the information gathered. I like this tool!