I made both a IJ and a GJ account during Strikethrough (the massive wank back in May of 07) but it was mostly just because fandom (or, well, my fandoms) was seriously considereing moving over there if LJ didn't sort out their shit. There's really no point to mine, but I know that some people use them as mirrors of their journals and actually update them, or post their fic on them and link back on LJ. IDK if any of that is helpful. I've never actually bothered to explore the sites themselves in any depth.

And I'm also wicked intrigued by that HDM/Narnia fic you've recced up there. *adds to the to-read list*