Vetiver is a perennial grass of the Poaceae family, native to India. Mats made by weaving Vetiver roots and binding them with ropes/cords are used in India to cool rooms in a house during summer. The mats are typically hung in the doorway and kept moist by spraying with water periodically. It acts like an air-cooler when wind from a fan or outside hits it. It also adds a pleasant aroma in the house which is commonly described as "cool" and "refreshing".
Vetiver is also an awesome folky offshoot of Andy Cabic based out of San Francisco. You might recognize Cabic from Devendra Banhart's Cripple Crow album, which he co-wrote and produced. Vetiver has been around for a while and often collaborates with Banhart and freak-folk sweetheart Joanna Newsom. I've posted a few songs from their latest effort "Tight Knit" on Sub Pop. Everyday is the most popular tune from the LP but its also the most sensitive. Through the Front Door is my favorite by far. If you can, definitely get this album. It's been perfect listening during Snowpocalypse 2010 and even better now that the Big Melt 2010 has started.
Through the Front Door - Vetiver (YSI)