I just uploaded a new version of Reaction Buttons, which features a widget now. In that widget you can show the top x posts with the most clicks for each button.
Coding took less time than putting the new version online, since there are a lot of places where you can set a version and they are parsed directly out of svn by some wordpress magic script. 🙂 I tagged the new release properly in the svn repository and added the version nubmer as stable in the parsed readme.txt. But I forgot to change the version in the main .php file, which seems to be important too. Thanks to #wordpress on irc.freenode.net for pointing that out. 🙂
Download from wordpress.org or directly through the install/update function of wordpress.