If you have an interest in photo editing (and who doesn't these days!),Pixlr
is a great online photo editor that runs directly in whatever browser you use. It's an easy to use app that comes with a wide variety of tools for whatever photo editing job you may have, whether you're creating a new image from scratch, uploading a photo from your computer or importing an image from the web.
Pixlr comes as either a complete photo Editor, amazingly similar to Photoshop, or as an Express photo manipulation app that lets you do fast, one-click changes to photos without getting too technical.
Pixlr's one downside is its lack of tutorials. Pixlr's blog provides basic how-tos, but other than that you’re on your own. Fortunately Pixlr is really easy to use, however some basic familiarity with photo editing software helps in achieving the sort of results you're looking for.
I'm running Pixlr in Google Chrome on my Linux Mint machines, and it does pretty much everything I need it to do photo editing wise. Give it a shot! You'll enjoy it whether you're new to photo editing or an old hand at the game!