If you have to ask, you probably don’t need it. But if you’re a hardcore audio engineer, odds are you already love SpectraFoo for its insanely powerful metering and analysis options. And you may still be booting an old PowerBook into Mac OS 9 just to run it, because SpectraFoo — until last week — didn’t do X. Metric Halo feels your pain, and an upgrade will cost existing users a measly US$149. Everyone else can get the software for $400 to $800, or bundled with one of Metric Halo’s highly respected audio interfaces:

SpectraFoo [Product information]
Foo Promotion

And if none of this means anything to you, well, you can just admire SpectraFoo’s Ghostbusters spirit detection / spaceship cockpit interface with the rest of us.