All Stack Exchange sites have a **giant** footer:  
[![Big footer][1]][1]

I don't need to have that extra space being taken up, so I built this user-style:

<!-- language: lang-css -->

    /**
     * Copyright © 2016 Jed Fox
     *
     * (The MIT License)
     *
     * Permission is hereby granted, free of charge, to any person obtaining
     * a copy of this software and associated documentation files (the
     * "Software"), to deal in the Software without restriction, including
     * without limitation the rights to use, copy, modify, merge, publish,
     * distribute, sublicense, and/or sell copies of the Software, and to
     * permit persons to whom the Software is furnished to do so, subject
     * to the following conditions:
     *
     * - The above copyright notice and this permission notice shall be
     *   included in all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
     * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
     * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
     * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     */
    #footer-sites {
    	display: none !important;
    }
    
    #footer #copyright, #footer #svnrev {
    	display: inline-block !important;
    }
    
    #footer #svnrev::before {
    	content: "//";
    	margin: 0.25em;
    }
<sup>try installing Stylish and adding this</sup>

This shrinks the footer:
[![Small Footer][2]][2]

The sites are available from the Stack Exchange dropdown at the top-left, and the extra line for the revision was bothering me, so I added it to the same line.

Here is a userscript if you don’t want to use Stylish:

    // ==UserScript==
    // @name         TopBar-Blur
    // @namespace    http://stackapps.com/questions/7091/34727
    // @version      0.1
    // @description  shrinks the SE footer
    // @author       J F
    // @license MIT
    // @grant        none
    // @match        *://*/*
    // ==/UserScript==
    var style = document.createElement('style')
    style.type = 'text/css'
    style.innerHTML = '#footer-sites{display:none!important}#footer #copyright,#footer #svnrev{display:inline-block!important}#footer #svnrev::before{content:"//";margin:.25em}'
    document.getElementsByTagName('head')[0].appendChild(style)
<sup>adapted from [this answer](http://stackapps.com/a/6970/34727)</sup>

  [1]: https://i.sstatic.net/QJB54.png
  [2]: https://i.sstatic.net/dCIE6.png