When I first saw this keyboard (and the next one on this list) my reaction was pretty much a hearty laugh and then a massive look of skepticism. A rubber keyboard? What? That just seems far too unorthodox and gimmicky to ever be legitimately usable and yet, after using it a few times, I think you'll pretty much agree that there is more to this than meets the eye.
Now, as you can see from the picture, it's made out of solid rubber and is built to be folded, rolled, or squished up to fit whatever spacial needs you have. This is great, because it's not as rigid as the Matias keyboard, and you can literally dunk this thing underwater and it still won't stop working. Washable, spill-proof, grime-proof, and dirt-proof make this one nearly alone in its class, but it has one massive downside -- because it's made of rubber the keys are much more difficult to push down on, and it requires a serious amount of finger strength. This means it takes a while to get used to, and for some people this isn't something they want to deal with.
But come on, when was the last time you could dump an entire bottle of water on your keyboard and then use it again in five minutes? Plus, it's only $10 or so online. Pretty decent deal if you ask me!