See this skyscraper? No, of course you don't, because it's invisible.
The squid-derived substance might sound fishy, but its color and light manipulation properties may be the key to creating a real invisibility cloak.
Artist Jimmy Kuehnle's transparent bicycle is the closest thing we'll ever get to an actual "invisible" bike.
Here's a fun invisibility trick that Magic Of Rahat used to confuse innocent and unsuspecting people working at a fast food restaurant.
See this bike helmet? No? That's because it's invisible. No, really, it is: that hefty collar that the bicyclist (or whatever) in the above pic is wearing contains a helmet-shaped airbag that deploys on demand to save your skull, and spends the rest of its time out of the way and looking fashionable.
Until we come up with a full-on invisibility cloak, we're just going to have to settle for making objects less visible in a few specific wavelengths, or alternatively, making them look like something that they're not. BAE's Adaptiv armor system can disguise vehicles in the infrared, making them look like cars, cows, or nothing at all.
There's still an awful lot that's not understood about how complex biological systems (like our bodies) really work. Part of the problem is that we can't just go look, since the only way to really see inside a brain (for example) is to cut it open, which by definition destroys its structure. Japanese scientists have a better idea: just turn everything transparent.
Metamaterials are things that are able to bend light into knots to such an extent that they can be used to render objects effectively invisible. So far this only works with objects so small that you can't see them anyway, but a new printing process can pump out sheets of metamaterial large enough for you to wear.
Big waves can be bad news for coastal areas, and over time, even moderate wave action can erode beaches down to nothing. In one of those schemes that sounds crazy but isn't, Chinese researchers have developed a system that uses concrete cylinders to render coastlines effectively invisible to incoming waves.
The last few invisibility cloaks we've seen have relied on metamaterials to make tiny objects invisible to a specific wavelength of light. This "carpet cloak," from MIT, uses some calcite crystals to make much larger objects disappear in the visible spectrum.