dhruwal

This plugin is useful when you want to know what date time & timezone is it on server where wordpress is hosted if you are in other timezone. 
Output looks like:
Server Date/Time: Sat 06th Dec,2008 11:17 am 
Server Timezone: America/Phoenix, (MST -07:00)
Version Change log:
v0.5 
Supports upto WordPress 3.7.1
v0.4 
Supports upto WordPress 3.6
v0.3 
Minimize css code 
Supports upto WordPress 3.5.1
v0.2 
Added description before date time 
Added timezone information 
Changed text color from red to green
v0.1 
Initial release

WP Server Date Time

This plugin shows the server local current date time & timezone in the upper right of your admin screen on every page.

Amin Raoufi

Admin Toolbar Live Clock keeps the current site time always in view while you work.
<blockquote>
Perfect for distributed editorial teams, agencies running sites in different time-zones, or any admin who regularly checks cron jobs, comment timestamps or scheduled posts.
</blockquote>
<h3>Who benefits?</h3>
<ul>
<li>Editors coordinating global content releases </li>
<li>Support agents logging activity against server time </li>
<li>Developers verifying scheduled tasks (Cron / Action Scheduler) </li>
<li>Multisite super-admins overseeing sites across regions </li>
</ul>
<h3>Feature highlights</h3>
<ul>
<li>Live ticking – updates every second; no page reloads, no Ajax polling </li>
<li>Calendars – Gregorian, Persian (Jalali), Islamic (Hijri), Hebrew, Buddhist (Thai) and Japanese </li>
<li>Languages bundled – English (en_US), فارسی (fa_IR), العربية (ar_SA), Español (es_ES), Français (fr_FR), עברית (he_IL), हिन्दी (hi_IN), 日本語 (ja_JP), ไทย (th_TH) (+ fully translatable via PO/MO files)</li>
<li>Time formats – 12-hour or 24-hour </li>
<li>Per-user timezone – keep the site setting or pick any IANA timezone </li>
<li>Colour-picker – separate, native WP colour-picker fields for clock & date </li>
<li>Admin-only & WPCS – assets load only in wp-admin for users with manage_options; codebase follows WordPress-Coding-Standards </li>
<li>Clean uninstall – removes all options on Delete via <code>uninstall.php</code> </li>
</ul>
Find the settings page at Dashboard → Settings → Toolbar Clock.

Admin Toolbar Live Clock

Real-time clock for the admin toolbar with multi-calendar, per-user timezone and colour controls.

WP Server Date Time vs Admin Toolbar Live Clock