Maybe I am a bit odd, but I think to solve a racial issue with emoticons by adding skin tone modifiers is actualy extremely racist.
An emoticon is meant to represent an emotion, obviously, and I think there should not be ANY racial association in them.
It worked great with normal smileys...no one gets offended by them.
Think of it this way: by creating "skin tone modified" versions you are forced to make a racial statement with every use of those emoticons...what a stupid idea...
Wouldn't it be much better to make those emoticons "generic" with yellow "skincolor" (or blue, green, purple or whatever non natural color one would prefer...)
What I am trying to say is that if you want to do something about racism, you won't accomplish anything if you force racial segregation upon communication.