I'm using the following matches to run on all metas and also on SO in Portuguese:.
Area51 is matched by *.se.com/*.
// @match *://*.askubuntu.com/*
// @match *://*.mathoverflow.net/*
// @match *://*.serverfault.com/*
// @match *://*.stackapps.com/*
// @match *://*.stackexchange.com/*
// @match *://*.stackoverflow.com/*
// @match *://*.superuser.com/*
// @match *://area51.stackexchange.com/proposals/*