I learned about the Melody Street website from someone on the MK8 List. Unfortunately, I can't remember who posted about it to give credit and I can't find the post in the archives.
Melody Street is an interactive website that is appropriate for the primary grades. You can navigate around the site and find different activities including games, music, stories, and short videos. The site is based around a book and CD that is for sale on the site. I haven't explored all areas of the site, but what I've seen looks good. There is one real annoyance for me though. It takes FOREVER for the different activities to load. If you plan to use this site with your classes on an interactive white board be prepared with short songs or finger plays to do while you are waiting for things to load.
There is also a Melody Street app for iPad or iPhone. The cost is $0.99. The app is more like an interactive book. The first chapter has been released and it looks like three more chapters are in the works. The book would be a great introduction to instruments of the orchestra for your younger classes. There is a different family of instruments that lives on each floor of the house. The book is narrated and there are a few objects on each page that are animated if you touch them. The sound of the instrument plays as each instrument character is introduced in the book. I'm actually more excited about the iPad app than I am about the website. I think I may use the iPad app in the classroom and then give students the link to the website to explore at home.
8/7/11 - Please also see the updated blog post I wrote about Melody Street.