This wiki page will collect great ideas for spectroscopy that have been expressed on the mailing lists or in person at barnraisings that could inspire a Spectral Challenge entry:

• I'm a gardener. Can i do my own soil testing? Usually i send away to a lab for a mineral profile, and to make sure there's nothing harmful in my soil before i plant food crops in it.
• I live near a refinery. How can i know what is being released in a smokestack plume?
• When I look out over my city, i can see what i call "the smog layer". It changes on a daily, even hourly basis. Can i tell how much (and of what kind of) particles are in the atmosphere over a city?
• I'm a surfer / fisherman / beach goer. Is this gunky stuff in the soil / on the beach just mud or is it a petrochemical?
• Can i test my tap water for additives?
• add your own here!
• and here