My first, small contribution to the community: a simple Emerald theme, partly inspired by the standard Crystal theme but using TruGlass engine to obtain some transparency and reflections. It works quite well with Pure Technology color theme and QtCurve or Polyester styles.
The shadow is tailored to nicely work with most wallpapers, almost regardless of where lighting comes from (but it will not be at its best if light comes from below).
Unfortunately, I can't remember where I got the buttons from! If the rightful designer wants to claim its due, I will be glad to quote him or her.
As usual, feedback is welcome.
UPDATE: now the QtCurve scheme shown in the screenshot is also included (both files are in a gzipped tarfile).