These are some of my favorite online image editors. Some are available online online, some are only available as apps on tablet devices, and some are available on both platforms.
Paid iPad app: https://itunes.apple.com/us/app/touchretouch/id373311252?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/touchretouch/id373311252?mt=8&uo=4&at=10l6SU
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
Paid Mac program: http://itunes.apple.com/us/app/iphoto/id408981381?mt=12&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/iphoto/id497786065?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/iphoto/id497786065?mt=8&uo=4&at=10l6SU
Free Mac program: http://www.gimp.org/downloads/
Free Windows program: http://www.gimp.org/downloads/
Paid Mac program: http://www.amazon.com/gp/product/B007USG342/ref=as_li_ss_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B007USG342&linkCode=as2&tag=edshelf-20
Paid Windows program: http://www.amazon.com/gp/product/B007USG3OC/ref=as_li_ss_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B007USG3OC&linkCode=as2&tag=edshelf-20
Website: http://www.wordle.net/
Website: http://pixlr.com/editor/
Google Chrome app: https://chrome.google.com/webstore/detail/pixlr-editor/icmaknaampgiegkcjlimdiidlhopknpk
Google Chrome app: https://chrome.google.com/webstore/detail/dpgjihldbpodlmnjolekemlfbcajnmod
Paid iPad app: http://itunes.apple.com/us/app/sumo-paint-create-draw-doodle/id542324634?mt=8&uo=4&at=10l6SU
Website: http://www.sumopaint.com/
Free Windows program: http://www.getpaint.net/download.html
Free Mac program: http://tuxpaint.org/download/
Free Windows program: http://tuxpaint.org/download/
Free iPad app: https://itunes.apple.com/us/app/tuxpaint-hd/id597240164?mt=8&uo=4&at=10l6SU
Website: http://pixlr.com/express/
Free iPad app: https://itunes.apple.com/app/pixlr-express-plus/id526783584?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/app/pixlr-express-plus/id526783584?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.pixlr.express
Website: http://pixlr.com/o-matic/
Free iPad app: https://itunes.apple.com/us/app/pixlr-o-matic/id450263811?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/pixlr-o-matic/id450263811?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=pixlr.OMatic
Website: http://ipiccy.com/
Google Chrome app: https://chrome.google.com/webstore/detail/ipiccy-photo-editor/imokeandodnlammaoenbgcnbhigjbpjh
Free iPad app: https://itunes.apple.com/us/app/morfo/id418900007?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/morfo/id418900007?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/morfo-3d-face-booth/id440560166?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/morfo-3d-face-booth/id440560166?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/shape-collage/id436917115?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/shape-collage/id436917115?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/instagram/id389801252?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.instagram.android
Free iPhone app: https://itunes.apple.com/us/app/facegoo/id317854296?mt=8&uo=4&at=10l6SU
Website: http://bighugelabs.com/