What accessories would i need to create a shot like this?

(minus the fish eye lens for the one pic)
btw i have a Nikon D90-

Added (1). The cheapest way also

Ultra wide angle lens…
if you want cheap, then don't do them kinds of shots… Try ones with the equipment you have to hand…

I'm presuming that you are looking for the lighting effect. You'll need an off-camera flash and some way to trigger it. Of course, you'll need the camera and it's metering as well.

I would argue you can do that with what you have. Lower the power of your pop flash and meter in manual mod to expose he background.

Well, what do we see on those pictures? A girl that got such a heavy dose of flash light that the ambient light in what appears to be bright sunlight was overpowered. That takes quite a powerful flash. Since the shadows on her neck are not completely sharp i assume that there was also some expansion of the light source involved, perhaps a small umbrella.
So what do you need? A reasonably powerful flash unit, first and foremost. If you have a flash that is compatible to Nikon CLS such as the SB-600 (i'm not sure if it's powerful enough for this extreme use though) or another way of using off-camera TTL (e.g. With a cord), then use manual mode with ISO at 200. Use a shutter speed of 1/200 (the max flash sync speed of the D90). Set the aperture to achieve an underexposure of about two or even three stops. The flash will then boost the exposure up to proper levels, thus illuminating your motive but leaving the rest pretty much in the dark as it doesn't reach that far.
If the flash does not support off camera TTL, then still set the camera as described above, but either calculate the flash power output or just determine it by trial and error.