You can actually flip the lens around and use it as a macro lens that way.
Since it's not going to be connected to the camera body, you're obviously going to lose the ability to zoom, and you'll have to focus by moving the camera to and from the object, but it actually works quite well once you get the hang of it.
The only thing I've found that's a pain is keeping the aperture open.
The aperture is closed by default, and opened using a little switch in the part of the lens that connect to the camera body. You can kind of see it in the picture above, it's on the right next to the screw. You'll have to hold that switch open in order to let enough light in through the lense to take any pictures.
Just be warned, there's a big downside to using this method, because you're holding the lense out in the open like that you're allowing dust and dirt to get into it.
You can get lens reversal kits, which are cheaper than getting an actual macro lens. All they'll do is allow you to connect the lens on backwards, and protect the backside of your lense from dust.