What type of Nikon wide angle lens do I need?

Could you recommend a super wide angle lens for me? I have a Nikon D60 and am using the AF-S Nikkor 18-55mm DX lens for most of my photographs. However I need to take interior shots of rooms and need a wider wide angle lens. I'm confused because my 18-55mm lens I thought was a wide angle lens (because it's focal length is less than 50mm).Is it worth me buying a new lens if my current lens already does 18mm? Is 18-55mm really a wide angle lens? I just feel like the lens I'm using (18-55mm) is hardly a wide angle lens and so what options are there for a super wide angle lens? Should I only stick with Nikkor or are other lenses compatible. Thank you for your help because I'm feeling pretty overwhelmed right now.

Try the excellent Tokina 11-16 ATX DX II. Tokina is a boutique lens manufacturer, started a couple of decades ago by Nikon engineers. Their best lenses (and the 11-16mm is one of them) are every bit as good as Nikon lenses.

I own the Tokina 11-16mm Dx (the difference being the Dx does not have a focus motor, while the Dx II has an internal focus motor that will autofocus with your camera).

Otherwise the closest Nikon lens is the AF-S 10-24mm Dx. The major difference is the Tokina is a fast f/2.8 constant lens, while the Nikon is a f/3.5~4.5. That means the Tokina could be used inside in available light, whereas the Nikon lens might require a flash. This is one time where I think Tokina actually has a better lens than Nikon.

And you will not really notice much difference between 10mm of the Nikon and 11mm of the Tokina.

Here is a comparison between what 10mm and 11mm looks like:

10mm:

11mm:

Or in other words, 10mm will give you about a 4% larger scene in the photo.

I use my Tokina extensively when we're on a cruise ship (we take 3~4 cruises a year), as it works well for interior shots.

The other "interior" lens I use is a Nikon 10.5mm fisheye. While it does result in the familiar fisheye distortion, it captures a lot more than even the 10-24mm Nikon. And you can use Nikon's Capture NX2 image editing software to "straighten" out the fisheye effect (at least somewhat, as there are still some artifacts left over from the post processing).

Here is an image I shot in Puerto Rico using a Nikon 10.5mm fisheye:

And here is the image corrected in Capture NX2:

The artifact in the straightening process does distort the foreground a bit though.

Also, the Nikon 10.5mm fisheye will not autofocus on your camera, but you can always manually focus it.