For people on a trip, and not carrying their Photoshop with them, here is a temporary replacement that could be useful: it’s called Pixlr, a website that works as an online photo editor, so no need to install anything, and it loads really fast!
It has 2 choices: Pixlr Editor (like a simple version of photoshop), and Pixlr Express (very basic, for cropping/resizing or fast adjusting).