If you already have a Coinbase account you probably are familiar with their quizzes where you get certain amounts of crypto by learning about them.
I just did this today and earned almost 30$ in no more than 5 minutes. I earned:
-10$ worth of XLM
-9$ worth of COMP
-6$ worth of MKR
-3$ worth of GRT
Pretty sweet for 5 minutes work, heh?