median filter?

[ichae]

I've got a set of pictures taken from on a tripod in rapid succession. It is a landscape shot so all the images are pretty much identical, except for CCD noise. I can combine them all into different layers, but now I want to take the median of each pixel to eliminate the CCD noise. But I don't see "Median" (or even "Average" for that matter) in the ways I can combine layers. Any idea how I can accomplish this; is there is GIMP plug-in out there that will do this?