Theta Music Trainer has a huge variety of different music training games on their site. You can sign in for free & play the first few levels of all their ear training games without paying for a subscription, which gives you access to the higher levels.
Topics include Scales, Intervals, Melody, Chords, Chord Progressions, Theory & Notation, Rhythm, Tuning & Pitch and Sound. If you have a microphone, you can even test your singing! Just playing regularly for a few minutes at a time will help improve your listening skills.
Other quizzes include: PLUC Weekend Workout – EarMaster Reference Songs For Intervals; PLUC Weekend Workout – On-line Ear Trainer; PLUC Weekend Workout – Speak Ukulele Challenge!; PLUC Weekend Workout – memrise on-line courses; PLUC Weekend Workout – Flashcard Machine; PLUC Weekend Workout – Music Reading Knowledge; A Question Of Uke – TV & Movie Themes