Pocket - When you find something you want to view later, put it in Pocket.
Yak Tack - remember. words.
Harken - Flashcard app using smart repetition to improve your memory
SmartCards+ - Spaced Repetition Software for iOS. Modern, powerful and easy to use.
Instapaper - Instapaper is a simple tool to save web pages for reading later.
memordo - Spaced repetition tool to help you retain more knowledge