Quick Link: Z-index and Positioning
In Andy Clarke's entry at 24 ways,
"Z's not dead baby, Z's not dead", he describes using z-index and absolutely position elements within a relative container. I've used this on projects in the past (with alpha PNG's) and it works well. Older versions of Safari and Netscape have issues under certain edge cases.
Um, the actual article seems to be here.
<shameless_plug>My photo blog makes use of semi-transparent PNGs and z-index for prettying up visual effects.
Is that a Zee or a Zed? :-)
Clarke is British and I'm Canadian so it's pronounced Zed (and rightly so! ;) ).
ps: thanks Ben, I fixed the link. :)