I do most of my photo editing on the Flickr web site. It's capabilities are fairly limited, but it does things like cropping, orientation adjustment (beyond just simple rotate) and basic color correction. They used to limit the number of photos you could store on the site, but if there is still a limit it's pretty high and I haven't hit it in a while. The other benefit, of course, is that you don't lose your pictures when your local computer dies.