This application is built on the speech sound analysis program Praat and is completely free of charge and available for many platforms. The idea is simple: A word is presented with a tone contour and you can then record your own voice and see how it compares to the model. This isn't 100% accurate, of course, but you can still see if it's in the right direction. I've had some problems adding my own word lists, but just using the default words should be useful.