Pocket - When you find something you want to view later, put it in Pocket.
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.
Keep Everything - Light & Fast Web Archiver for iOS, OS X.
Yak Tack - remember. words.
WebSatchel - Copy and save web pages to your own personal archive
Zorbi - Spaced-Repetition Flashcards - Other tools are built by boomers, Zorbi is built by students.