I must admit I had to Google this when I heard an article about this on the radio, as I had no idea what Loom Bands were.
Loom bands: Exclusive designs from drinks holders to butterflies for you to try at home - Mirror Online
Child's dress hand made from Rainbow Loom Bands fetches €215k on eBay - Independent.ie
As far as I can make out, it's basically a new twist on the "French Knitting" that we used to do as kids, with a cotton reel & 4 panel pins, only with custom made elastic bands, which sell for about 1p each. 1p each may not seem much, but it looks like it can soon add up when it comes to larger projects.
The thing is, that now it seems that these are being banned on H&S grounds in schools, as they're causing arguments & fights in the playground (so, what else is new with kids?).