Robert Wetzlmayr

This simple and lightweight WordPress maintenance plugin puts the site into maintenance mode by sending a ‘503 Service Unavailable’ status to all unauthenticated clients.
Thus it effectively inhibits search engines from both losing your site’s existing content and indexing your maintenance page as well, so your site will not lose its rankings while it is out of service.
Content will even be hidden from consumers of the site’s RSS or Atom feeds.
Please refer to the <a href="http://talkpress.de/blip/wet-maintenance-wordpress-plugin" rel="nofollow ugc">WordPress Maintenance Plugin</a> article for additional information.

Site Maintenance

Puts the site into maintenance mode by sending a '503 Service Unavailable' status to all unauthenticated clients.

DrMosko

<a href="http://www.dossihost.net/%D7%AA%D7%95%D7%A1%D7%A3-%D7%95%D7%95%D7%A8%D7%93%D7%A4%D7%A1-%D7%A1%D7%95%D7%92%D7%A8-%D7%90%D7%AA%D7%A8-%D7%91%D7%A9%D7%91%D7%AA%D7%95%D7%AA-%D7%95%D7%97%D7%92%D7%99%D7%9D/" rel="nofollow ugc">WP-Shabbat</a> is a WordPress plugin that will help you and your visitors observe the shabbat.
For more information in hebrew, check out <a href="http://www.dossihost.net/%D7%AA%D7%95%D7%A1%D7%A3-%D7%95%D7%95%D7%A8%D7%93%D7%A4%D7%A1-%D7%A1%D7%95%D7%92%D7%A8-%D7%90%D7%AA%D7%A8-%D7%91%D7%A9%D7%91%D7%AA%D7%95%D7%AA-%D7%95%D7%97%D7%92%D7%99%D7%9D/" rel="nofollow ugc">WP-Shabbat</a>.
Features include:
<ul>
<li>close the site by setting the Shabbat and holiday enter time in minutes when the minimum is 20 minutes.</li>
<li>close the site by setting the Shabbat and holiday exit time in temporary minutes from 18 minutes to 72 minutes.</li>
<li>Ip databse is updated automatically every week. (est. size : 17Mb)</li>
<li>search engine bots get http header 503.(SEO-Friendly) : 
<a href="https://productforums.google.com/forum/#!topic/webmasters/bjpQtTwzadI/discussion" rel="nofollow ugc">Answer from Google about WP-Shabbat</a></li>
<li>plugin languages : English,Hebrew,Russian.</li>
<li>plugin will generate on fly page with your template for visitor to come back later.</li>
<li>Display popup message when its shabbat or holiday.</li>
<li>Display one hour countdown before site closes to soft the user termination.</li>
<li>Add custom messages and images etc, below the plugin default message.</li>
<li>select which css class/id to hide when site closed.</li>
</ul>
Notes:
<ul>
<li>Shabbat and holiday exit time is temporary minutes that calculated from sunrise to sunset and divided into 12 hours.</li>
<li>The sunrise and sunset times is calculated for each user by his location. </li>
<li>Identification place of the user is by its IP address close to 40 km.</li>
<li>This script uses GeoLite Country from MaxMind (http://www.maxmind.com) which is available under terms of GPL/LGPL </li>
<li>DB file GeoLiteCity.dat downloaded every week from maxmind servers to plugin directory.</li>
</ul>

WP-Shabbat

Close site or display popup message on Shabbat and Holidays by identifying the address of the user IP and close to 40 km

Site Maintenance vs WP-Shabbat