Power15

It starts you off at a base rating and you grow in each category the more you answer. Every category is rated separately, so you could train National level History questions whilst also learning Novice music. You can make your own sets with unique distributions to practice just the way you want. Look back at your answers and know exactly what you buzzed at. All of this whilst having access to over 55000 questions from QuizDB at your fingertips. Moreover, the app doesn't require internet access, meaning you can take the app with you everywhere you go. (One time login is required)
Currently in Beta testing and access is limited, contact the developer for access to an account.