Why does it have to be 100x100? Most forums with avatars resize the images sometimes. Why sacrifice poor yoshi's nose? But, the hat however, can use a little more tilting. There's a couple things you could do with it. Either move it over more to the right so it covers the eyes just a little bit, or turn it around the opposite direction. Both of which I don't think will hurt the image. Please try to finish his nose? Or shorten it a little. Nice palette by the way. One more highlight couldn't hurt on the darker brown I think.