Triptico
http://www.triptico.co.uk
This is an amazing downloadable suite of classroom flash tools. The collection includes timers, word magnets for pupil names and other words, team point scorers, sentence ordering tools and more. It’s a must have resource for any teacher to have in their toolbox.
Jam With Chrome http://jamwithchrome.com This is an amazing site which allow up to 4 people to collaborate and play virtual instruments over the web in real time. Play a variety of guitars, drums and drum machines and keyboards. There is no sign up needed and you just invite other 'musicians' by sharing the link and begin jamming. Set to 'pro' mode to play using your computer keyboard. Requires Google Chrome.
Project Noah
http://projectnoah.org
This is a great citizen science site where users can upload and view photos of animals or use the free Apple device and Android Apps. It's a great way to do real science with what you already have in class. Check out the education section for more ideas.