For those people that need minor or midium image manipulation I do often recommend Gimp. Unless you are an Adobe Photoshop fan or a professional designer with some very specific needs, Gimp can do the job for you and save you some money along the way.
While Gimp itself works great, there is a lack of documentation (in terms of tutorials, tips, and tricks) compared to Adobe Photoshop world. There are a few at Gimp’s website, of course. But there are few other resources if you know what I mean.
Gimp guru is just such a resource. It has a few tutorials, links to mailing lists/forums where people can talk and even provides a “Ask your question” section. The site is oriented towards the photographers mainly, but it can prove useful for other artists too.