Can anyone recommend a good ebook, website, self-study course, etc. to help software engineers, programmers, etc. gain a basic knowledge of graphic arts. I'm interested in basic Photoshop/GIMP skills to help make and tweak icons, images, etc. when I don't have a professional graphic artist nearby to help out or if the job is too small to hire one.
If what you're wanting is to actually learn graphic design, well that's a big topic. However for simply learning how to tweak images in Photoshop there are plenty of great free resources online. Here's one of the first results when I just searched for "photoshop beginner tutorials"
http://mashable.com/2010/08/12/12-beginner-tutorials-for-getting-started-with-photoshop/
Also, you'll find lots of great info at the graphic design Stack Exchange site: