In reply to Rick Graham:
Yes, open dislike/like would be best. Quite often one cannot be bothered typing a response but would love to make it clear a particular post is rubbish. Signing a like/dislike would make registering your support or, more often, telling a poster to f*ck off much easier. Anyway, I would not want to post anything I would not also say to anyone face to face (my use of a pseudonym is for practical uses only, anyone could deduce who I am or simply ask).
CB