Screenjelly records your screen activity with your voice so you can spread it via Twitter or email.
Use it to quickly share cool apps or software tips, report a bug, or just show stuff you like.
Basic function and interface reminds me of GarageBand (shame no Midi support!) but it's a very impressive web based app! The real change is their approach to collaboration and derivatives as all Myna files are saved to their server for all to see and modify on the free account... "Please note that making creations private is restricted to Pro members."