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

* can i do my own soil testing? Usually i send away for a mineral profile. 
* how can i know what is being released in a smokestack plume?
* can i tell how much (and of what kind of) smog is in the atmosphere over a city?
* is this gunky stuff in the soil / on the beach just mud or is it a petrochemical?
* _add your own here!_