Type "Shiflt + L" to Like/Unlike & Fav/Unfav on Tumblr Dashboard. Click the label "raw" below to install.

love_on_tumblr.user.js

// ==UserScript==
// @name           love on tumblr
// @namespace      http://www.tumblr.com/
// @description    love current post on tumblr dsbd with 'Shift + l'key. if won't work, pray on tumblr!
// @include        http://www.tumblr.com/dashboard*
// @include        http://www.tumblr.com/show/*
// @include        http://www.tumblr.com/tagged/*
// @version        0.0.2
// ==/UserScript==

if(!window.Minibuffer) return;
var $X = window.Minibuffer.$X;
//var submit_like = function(id,t){ unsefeWindow.submit_like(id,t); };

window.Minibuffer.addCommand({
  name: 'tumblr.Like',
  command: function(stdin){
  stdin.forEach(function(obj){
    var id;
    if ( (obj.className.match(/not_mine/) && (id = obj.id.match(/post_([\d]+)/)[1]) ) || (id = obj.id.match(/(tweet_[\d]+)/)[1]) ){
      $X('.//form[starts-with(@id, "unlike_form_")]', obj).forEach(function(e){
        var t = (e.style.display != 'none').toString();
        location.href = 'javascript:submit_like("' + id + '",' + t + ');'
        // submit_like(id, t);
      });
    }
  });
  return stdin;
  },
});

window.Minibuffer.addShortcutkey({
  key: 'L',
  description: 'tumblr.Like',
  command: function(){
    var stdin = [];
    try{
      stdin = window.Minibuffer.execute('pinned-or-current-node');
    } catch (e){}
      window.Minibuffer.execute('tumblr.Like', stdin);
      window.Minibuffer.execute('clear-pin');
  }
});