There are a few open source options out there allowing you to edit pictures for free featuring some Photoshop goodness. Gimp and Krita both offer solid alternatives to Adobe’s flagship image editing software, but they involve a lengthly download and install if all you need to so is quickly edit an image on the fly.
I recently stumbled upon a couple of great online photo editing sites – Splashup and Pixlr . Both of these systems allow the PS features we love like layers, drop shadows and gradients. Splashup allows both online image editing and a download of a lite version of the software and cleverly allows you to start editing images from Flickr, Facebook, Picassa etc.
You should find Splashup particularly user friendly, with the additional social platform integration and downloadable lite version, it has has the edge.