At the Bluefire Blog, Micah Bowers, the designer of Lightroom's Flash galleries, shows a method for adding background sound. Wisely, he adds

Sound that automatically plays in websites is appropriate in some circumstances, and terribly annoying in others. This can be particularly true when you don?t offer volume controls or a mute button (which this movie does not have). So please be thoughtful about where and when to use this. When I have more time, I?ll make one with at least a mute button and post it.

Just like the warnings on fag packets (for American readers “fags” is English for cigarettes), somehow you know people will eagerly inflict their musical taste on unsuspecting visitors. At least Micah says he'll work on a version with a mute button. And bring on July 1st too.