Super quick update: We've now added transparency settings. Try it out under the "Advanced options" in the "Themes and Colors" section - and be sure to call out any designs you're particularly proud of in the comments. We'd love to show it off in the list of channels on the right hand side of this blog. In fact, you can now modify two different levels of transparency: One for the modules, and one for the wrapper. (The wrapper can even be completely transparent.)
Also fixed: The bug that occasionally caused Firefox / Chrome / Safari to crash.