Tim Thompson has setup a nice and easy to use Web interface to a number of applications he has created.
I had loads of fun creating my own music and I have absolutely no musical talent. I was amazed at the quality of music that can be created by pure trial and error. These "toys" are much more powerful than they appear.
Be sure to try out the Muse-O-Matic and Pieces of MIDI. I suspect that you will find yourself playing with Tune Toys for many hours.