Maybe... OMG I'm going to say this!!
"Just" buying, porting and "xenforing" Post Rating itself? /me running away screaming!
I don't know if this is, or will be, a KAM's practice. But IMHO have a system like that in the core can be a great improvement in user engagement aspect, and why not, a little KA against other forum scripts.
and maybe @Luke Foreman will create another great and brand new add-on!! ...and many little Like System Extended "extensions".
What do you think of this?