I like listening to music while I work. I also like notification sounds – such as gaim chiming when messages are received (so I look at them) and such things.
I use an iMic USB audio dongle to output sound to my headphones (partly because the connector on my laptop is a bit dodgy now) and I’ve detailed in the past how support for hotplugging of audio devices leaves a lot to be desired (it’s worse than it used to be sadly – I used to just be able to run esd against sound device and all was hunky dory).
What currently gets me is that music can be an adequate volume and then WHAM this loud gaim notification comes through.
Setting gaim to be softer and music to be louder isn’t immediately obvious and is easy to get wrong. It’d be great if the Volume Control applet could tweak it all from one place (and there was a way to change what the drop down volume applet controlled).
pulseaudio (formerly polypaudio) will solve your problems.