Don't like the red #43, but I do like #42. I'm really liking this one but it's hard to make out the M you are talking about. The colors are great though :). Any other versions? Possibly one that will look good when shrunk down to 16x16 for the bookmark image.
Each one of the colour strips is an M shaped icon and also the the three M strips together form an M icon too. I still believe it will look good shrunk down, but I'll try and see what I can do, But I don't want to sacrifice it looking great normal size just so it can be seen tiny.