I don't know about anyone else, but I like metamoderating because sometimes I find interesting discussions that I missed, or new posts on discussions that I've seen and am interested in, but have forgotten to keep track of. If only you could mark discussions to be watched for new posts, or if only I was ambitious enough to write my own interface to do the same thing...then again, I kind of enjoy the randomness of the metamoderation system, it's kind of like hitting 'shuffle' on your CD player :-)
Here's an ethical question. Is it ok to respond to a comment or a thread that you metamoderated in? It surely isn't right to moderate something you also participate in, and metamoderating is only a step removed.
