I use Quizlet for exactly this (https://quizlet.com/). Works great. I paid for the "Plus" plan and am happy with it. (I can't recall if I needed the paid version or just wanted to support the project, but recall being pretty happy with the free version too).
Lots of great Flashcard apps out there. Definitely a great way to learn - especially things that fade quickly if not using them regularly (looking at you, Powershell ;-p ).
gwern is an amazing resource and has great articles on a range of topics, including productivity stuff; his posts on nicotine [1], modafinil [2], and melatonin [3] would be 3 highlights.
