The SpaceTime Reading Challenge is a challenge focused on reviewing sci-fi of any sort. Whether that be a futuristic society living on Mars, a grand adventure across space, or a simple story about a robot. Anything sci-fi goes.
The A-Z Reading Challenge has everything you need to know in the title. You read books with titles that begin with the letters of the alphabet.
The Goodreads Reading Challenge allows you to aim for a target number of your choice, and read whatever you want. I'm aiming for 52 books.