Here's what the Rainbow Loom looks like. The bands are stretched over the pegs in a pattern and the hook is used to weave them. It looks somewhat like loom knitting to me, but I've never done either one, so I don't really know.
Different patterns will result in different final products. Here are two that were made this weekend.
I was afraid when I bought all the bands, that the boys would be jealous that I didn't get anything for them. Not so. Turns out it's a good thing I stocked up on the bands and got another loom. This seems to be a popular pastime with everyone around here.