This resource is very much like Google Classroom, but designed particularly for music educators. Useful for teachers, students, and parents, this site is a management tool for music programs large and small. Keeping all of your constituencies on the same page can be a chore, but not when you streamline collaboration with iSchoolMusic.org.
Every time I need parent volunteers for school events, Google Forms is my go-to resource to aggregate volunteers in an organized and simple manner. Potential volunteers are greeted with an aesthetically pleasing form to complete, and results are displayed in an easy-to-read spreadsheet. If your students have access to computers in the classroom, this is also a terrific resource for creating basic assessments to check for student understanding.
I use this resource often as a way to randomly group my students, select students in an equitable manner for instrumental or speaking parts in school musical performances, and offer a truly random numerical selection for questioning students by their class "numbers." There are testimonials on the website that speak to the usefulness of this product is the compositional process as well!
I use Google Classroom primarily for my band students, and have had great success in keeping students engaged in directed weekly practice and assignments. The ability to upload recordings and videos makes this tool a useful way to stay connected with students throughout the week who I only see in class one time per week.
This FREE music notation software is powerful and intuitive. I own Sibelius 6, and still use Muse Score because it's so good. The "help" section is a very useful forum, and teaches you lots of shortcuts and tips to make notation less cumbersome. I use this for both my general music and band notation needs.