Image Watermarking

You can add a watermark in most graphic programs.

Here are a few resources, too

http://www.vicman.net/lib/easy-watermark.htm

http://www.easyimagetools.com/products/watermark/index.htm

http://www.softplatz.com/software/watermark/

shareware- so if you like them you have to purchase
http://www.easyimagetools.com/products/watermark/

http://www.evinco.com.hk/eng/photox.html