Courseroot - Biggest online course database on the web
Agenda - A date-focused note taking app for both planning and documenting your projects.
Learn Anything - Search Interactive Maps to Learn Anything
Notepin - Extremely simple note-taking + blogging ✍️
Stacks - A bookshelf for your online courses
Bear - Bear.app is a note-taking and content writing app that helps you boost productivity with its intuitive tools.