The MIDI Sprout enables you "to listen to your plants play harmonious sounds" based on changes in conductivity on their leaves. From the company's background story:
The richness of this data inspired me to give plants full control over every note played as well as control over effects. I scaled the instruments into the key of C so the music was harmonious. I created parameters for the rate at which the instruments could be played to provide a resolution that was both musical and close to real time. Then I just let the plants do their thing.
This was not a particularly high quality final. Its ebb and flow was usually reliant on one of the players failing or erring rather than succeeding or winner-ing (with a few notable exceptions). But holy moly was it chock full of drama.