Playlist.com (http://www.playlist.com ) is the epitome for music in connection to the 21st Century Learning Skills of Create, Collaborate, and Organize. (http://www.p21.org). You can read my thoughts (long form) about it here: Technology Tim's Blog Post on Playlist.com
Free access to lesson plans, blog, resources, graphic organizers, collaborate with other educators using brainpop, interactive whiteboard resources, etc. You can also request an embed code to embed their feature movie right into your wiki!!
This powerful tool is sadly one of the "best kept secrets" of CMS. Students will be engaged in the reading and writing if introduced to the awesome power of Kerpoof. Integrate with your Lab Teacher and get students being creative and writing. Free.
An easy to set up, powerful to use, Learning Management System (LMS) that looks like Facebook and can get your students discussing ideas and collaborating. One of many webtools that Tim and I are providing PD for in our 21st Century Technology Skills and Tools training in MyPD.