Look, it's not going to replace Photoshop, but there are a number of image editors that you can easily install on Google Chrome for quick fixes and tweaks. Perhaps the best known and most widely used are a trio of editors from Pixlr, that offer differing levels of control and power. They have Pixlr-o-matic, Pixlr Express, and Pixlr Editor, in ascending order of complexity. Pixlr-o-matic is your Instagram-like, faux-lomo, add filters to all your images app. Not exactly high-end, but people really like it. Pixlr Express allows for quick editing of photos with a number of tools and effects, in line with low-end image editors. You can tweak contrast, blur and deblur, throw on some filters, and call it a day. Pixlr Editor is the most advanced of the lot, and presents an interface pretty well known to anyone who's spent a bit of time behind Photoshop or GIMP. All three of these apps are also available as webapps through Pixlr's website.