Free Android Phone app: https://market.android.com/details?id=com.evernote.skitch
Free iPad app: http://itunes.apple.com/app/skitch-for-ipad/id490505997?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/app/skitch-for-ipad/id490505997?mt=8&uo=4&at=10l6SU
Free Mac program: http://itunes.apple.com/app/skitch/id425955336?mt=12&uo=4&at=10l6SU