Driven (aka LoneWebSurfer) of BoardMod & the YaBB Team, has published a new Y2.3 template called... O-opacity [2.3].  This template is configurable and great looking.  Here is a quote from Driven:

O-opacity is a very versatile template. it uses .png images to give it a transparency. If you have been to any MySpace pages..then you will have already seen a ton of those layouts done like this.  
it allows for any background to be used of any shade! Altho I set it up for a darker theme..with just a few edits of the style sheet..you can easily use a light..even white background!