There are stairs going up the east side of Skógafoss, all the way to the top. About halfway up there is a short pathway out to a smallish overlook of the waterfall. And on the outermost edge of the overlook is a narrow jut of rock dangling out over the drop off. If one clings tightly to the rock, it is possible to get out on that overhang and have an absolutely unparalleled view of Skógafoss.
I may have given Rachel multiple heart attacks getting out there and back (three times!) but it was worth it.