Sup every1, i'm wondering if there is a plugin, or perhaps some free standing application, that lets you use an entire image as convolution matrix? Or at least some images to demonstrate what the result of this might look like? I'm especially interested in using an image to convolute itself, but combining different images may give good results too. If there isn't one already, this would be a really good thing for someone here with plugin programming skills to try.....

Do you mean using a kernel like this filter?
Filters → Generic → Convolution Matrix.
8.2. Convolution Matrix

Yeah, but with an entire image as the matrix, instead of a 5x5 set of pixels...

G'MIC has more options, Contours / Convolve.

No idea what you're talking about at all, don't think that has anything to do with it.

G'MIC is a must have plug-in for Gimp.

G'MIC convole info
Command line and GUI in Gimp.

The proper way to convolve an image with a big convolution kernel (here another image) is to perform a multiplication in the Fourier domain.
Implementing the direct convolution formula take ages otherwise (indeed, complexity of the explicit convolution is O(w*h*wk*hk)), where w,h is the size of your image and wk,hk the size of the convolution kernel.
There is one command in G'MIC that computes the convolution between two images, through the Fourier transform, but no filters for the plug-in for GIMP that uses this command actually.
It usually doesn't give very interesting results (from an artistic point of view). Below are some examples of convolutions of an image with another images.
The results have been normalized in [0-255] to make them visible.

Okay, so what would i need to perform this myself?

Do you have GMIC installed?