Pocket - When you find something you want to view later, put it in Pocket.
Harken - Flashcard app using smart repetition to improve your memory
MemoStack - MemoStack is a flashcard software that help you memorize more things with less effort. It works great for test preparation, language learning, and more.
Instapaper - Instapaper is a simple tool to save web pages for reading later.
Locked.app - Do you often forget if you've done something important?I keep coming back to check if I've locked the doors.You can check the toggle when you close the door or something.
Keep Everything - Light & Fast Web Archiver for iOS, OS X.