Natural Search Blog - Alt tags

If you have gifs or jpegs on your webpage, it's good practice to implement ALT tags to help crawlers know what your graphics are about. Generally speaking, the overall SEO impact of ALT tags is low, but offers another opportunity for boosting keyword frequency. Learn more:

http://www.allbusiness.com/articles/EBusiness/3296-2804-2809.html
http://www.perfect-optimization.com/image-alt-tags.htm
http://www.a1technology.com/blog/2004/10/using-alt-tags-is-very-important.htm