Application level volume control in OS X?

I recently switched from PC to Mac and one thing I miss is Windows' application-level volume control (i.e. mute Firefox, turn up iTunes, turn down Skype etc). How can I achieve the same on a Mac? Or better yet, I want volume settings based on location (using HTTP location API or WiFi network name) and time of day or day of week etc.

Solution 1:

A free and open-source solution is BackgroundMusic.

A nicer and paid solution is Rogue Amoeba's SoundSource

Solution 2:

Detour is no longer under development, and doesn't work in MacOSX 10.5+

Hear is a rather expensive utility ($49.95) and has a number of other audio "Pro" features.

Jack is a low-latency audio server written originally for GNU/Linux and I believe can change volume on a per-application basis. And it's free.