Rubber bands by Silly Bandz are made of silicon and are die molded into fun shapes: Harry the Catterpillar; Igor the Spider; Betty Jo the Butterfly and more. My personal favorite is Speedy the Snail!
They look and behave like normal (albeit colorful) rubber bands when stretched. But when removed from whatever they are holding, they instantly spring back into their original shapes! Flick them at your co-workers, use them for wrapping presents or horde them all for yourself. What a great gift for students or parties.