I have a large div with the site header/logo as the background image. Is there anything wrong with putting a h2 tag containing the site title behind this using z-index, so that it would show if the user couldn't/didn't get the image for some reason? I know this is different to a standard [background on the h2 element] image replacement. (EDIT: Sorry maybe i'm not making it clear - i'm using a div background image not an IMG tag)
If possible, I would ditch the div and just use an h2 with an id and set a background image to that.
I do that whenever possible to avoid excessive divs when I could use other block-level elements, if it only has a background and text. An h* with a background image is still a heading.