I just stumbled across a great web-based tool for musicians: Noteflight. If you want to compose, and share your works with others, this site is perfect. Users can save their creations in an individual account, and email a link or embed the score on a blog or web-page. There's even a teaching module (which costs $) for music instructors to use.
Compositions can be printed or exported in a variety of formats (you need the latest Flash plug in installed) such as midi or wav files. The online documentation is very extensive and give a good idea of what this program can do.
A great tool, especially for Music Composition and Technology teachers!
Here's a sample I created:
