If a Pogoplug had a microphone plugged into it, and we know USB mics are between a dime a dozen and $99 for a Blue Yeti, we could make an ambient noise map over time.
This is inspired from people who need to record acoustic guitars, and neighbors/street noise are too loud. They could record at night, but that kills the vibe. There are holidays the neighbors leave, Sundays maybe neighbors go church, nights out to wherever etc. If the Pogoplug was running the right software it could take note of say 10 bands across the 20-20Khz frequency spectrum and map them into a biofeedback chart.
So it's like surveillance but only audio and even then just taking note of frequency levels. Those could even be converted to tiny MIDI files and analyse in a calendar type time evolution. You could probably even make a trigger where the volume is so high it records what's going on, but your significant other may not be happy so just leave it at MIDI.
There are a lot of home recording studios across the world, and these people many times buy or make acoustic panels, but that doesn't cut out the noise that gets through windows and whatnot. If after some time you see there's a two hour lull at 3PM, this might make all the difference in a music recording or for that matter any audio that goes to media, and face it, having a slightly better recording yields higher quality persuasion you want for your end user.
Lastly, in Windows you could:
1. Just record and leave it on, record to FLAC or MP3 and visually check the wave heights, or better yet
2. an audio-to-MIDI converter and tell it to make an observation once every minute or five minutes,
but I don't know how to graph that to a calender and especially don't know how to do that in Linux. To that end I'll be working on various Linux Multimedia studios and checking ut what's available, but if you get there first, have fun!
In the end, for the audio people in your life, is there a better way to spend (realistically) $20+ ?
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-= Cloud 9 =-