Pixlr: free effective and easy to use online image editor
Swedish Image Editor Pixlr offers a fast and intuitive software for those who need basic image editing capabilities. As stated on their website:
Pixlr is built for non-professionals, the users that have basic editing needs. It's not for large RAW images or for printing. It is merely a tool for editing web images to be posted on blogs, news-sites, social networks like Facebook, Myspace Bebo, image sites like Flickr, Fotolog, Photobucket etc.
I have started using Pixlr for editing the images for this blog and I'm very happy with the results. One handy feature I use a lot is the ability to open an image from the web by entering its URL. Pixlr is built in Flash, so you need to have Flash Player installed to run it.
Besides the photoshop-like image editor, Pixlr also offers a very intuitive software called Photo Express. Open your picture (from your computer or the web), and in a few clicks you'll be able to crop it, rotate it, adjust brightness and contrast, or apply very interesting effects.
Try Pixlr here.