webbu

You can install Webbu Mobile Framework Theme Switcher (WMF Theme Switcher) plugin into your desktop website and choose another theme for mobile devices without affecting your desktop theme.
Detects all the Mobile Browsers and loads the mobile theme per your settings done in the admin.
<ul>
<li>iPhone</li>
<li>iPad</li>
<li>Android</li>
<li>Windows Mobile</li>
<li>Blackberry</li>
<li>Other Tablet Browsers</li>
<li>Other Mobile Browsers</li>
</ul>
You can select a different mobile theme for each mobile browser. You can select different mobile themes for each of the options above.
Webbu Mobile Framework Theme Switcher using <a href="http://mobiledetect.net/" title="mobile detect" rel="nofollow ugc">Mobile Detect</a> library to detect devices.

WMF Theme Switcher

This plugin switch themes per mobile and tablet device. Useful for the switch to a mobile theme.

KilukruMedia

Mobilize your WordPress! Automatically detects all the Mobile Browsers (more than 5,000+) and loads the theme as per your settings done in admin.
<ul>
<li>Iphone / Ipod</li>
<li>Ipad</li>
<li>Android</li>
<li>Windows Mobile</li>
<li>Windows Phone 8</li>
<li>Blackberry</li>
<li>Parm Os</li>
<li>Opera Mini</li>
<li>Others Mobile/Non-Mobile Browsers (more than 5,000+)</li>
</ul>
You can select a different theme for each mobile/non-mobile browser. WP-Mobilizer plugin also includes an installer that will configure everything automatically. All you have to do is install and activate the plugin.
<ul>
<li>Automatic detection of mobile/non-mobile devices.</li>
<li>Differentiates between standard mobile devices and advanced mobile devices.</li>
<li>Detects more than 5000+ devices.</li>
</ul>
This plugin uses the <a href="http://www.mobileesp.com/" rel="nofollow ugc">MobileESP</a> by Anthony Hand as its detection script (under Apache License 2.0). For more information please visit our website: <a href="http://www.wp-mobilizer.com" rel="nofollow ugc">www.wp-mobilizer.com</a>

WP-Mobilizer

WP-Mobilizer detects over 5,000 mobile devices and displays. You choose the theme you want for devices. Usefull for switch to Mobile Theme.

WMF Theme Switcher vs WP-Mobilizer