I remember learning the basis via a wonderful website designed to teach quantum computing (qubits, Bloch sphere, doors up until explaining Shor) with recurrent quizzes, whose content depended on what you had good/wrong on the previous one. Though I can't find a mention of it anywhere, HN submissions/comments or search engines.

As I'd like to brush up my knowledge, any recommendation of the best resources to get a 101 on the subject?