So a while ago I blogged about how much I despised sound coming from my browser, especially from Flash files. Nothing is more annoying than having my browser play music when iTunes is playing at the same time. This isn't a complaint about Flash (although I wish the player had a mute itself) but rather developers who somehow feel the need to assault my ears with crap. (To be honest, it's probably not the developer but the client who insists on playing music automatically.)
There was a program called FlashMute which promised to silence any Flash applications in the browser. At the time I tried it, it didn't work well for me. However, a new version was released recently and so far, it has worked perfectly! (I'm using it with Firefox 1.5 and Flash 8.5.)
This program is free and pretty light weight, so I highly recommend it to anyone who is as annoyed by music from their browser as I am.