Higurashi Jan has them also. But they’re not from manga artists and I can’t recognize most of them. Is there anyone saw them before?
the third image is illustrated by this artist: http://www.pixiv.net/member.php?id=710768
and the second image is by this artist: http://www.k4.dion.ne.jp/~aqmari/ff.html
some of the others also look painfully familiar, but I’m not sure about the artists for any of the rest, sadly.