"2) a linked image where the image is the ONLY thing within the link, in which case the alt text should describe the destination of the link, not the contents of the image. I just recently learned this, but it makes sense when you think about it. "

Yeah. Good stuff. Thx.

p.s. Best I can tell most images are decorative. That is, they are there for the visual appeal, to create "white space", etc. It's fairly rarely they actually contain content. Of course, there are exceptions, but in general.