I'm an enormous quiz geek, and under the pretensions of it furthering my knowledge, I'll happily spend hours on a website called sporcle.com.
Better than me describing how it works is you giving it a go - it's got a very satisfying way of working the quizzes and filling in the answers. I'm obsessed by the geography quizzes (and can now name all 195 countries in the world in about 7 minutes, which is probably going to be the peek achievement of my life - all downhill from here then!), but on a music tip they have some cracking quizzes. So if you think you can name all the Bob Dylan albums, or all the tracks on Thriller, or all the instruments in an orchestra, or know who William Bruce Bailey is better known as, then sporcle.com is where you can put yourself to the test.