Code96

This plugin easily detects mobile devices and redirects them to the mobile version of your site. This plugin also gives you the ability to bypass the mobile redirect based upon a cookie that is set on your mobile site. This allows you to redirect mobile users and give the option to “View Full Site.”
If you are upgrading you must enable the redirect via Settings > PHP Redirect
To set the cookie simply add the following PHP code to your mobile site:
setcookie(“mobile”,”m”, time()+3600, “/”);
The mobile redirect bypass cookie is optional, and should only be used to give your users a “View Full Site” option
Code 96 offers <a href="http://www.code96wd.com" rel="nofollow ugc">WordPress Design</a> services and custom <a href="http://www.code96wd.com/premium-wordpress-themes/" rel="nofollow ugc">WordPress Themes</a>.

PHP Mobile Redirect

Easily detect mobile devices and redirect them to the mobile version of your site.

Joe Rhoney

AddFunc

Uses <a href="http://mobiledetect.net/" rel="nofollow ugc">Mobile Detect</a> to redirect mobile traffic to your mobile website.
<ul>
<li>
Redirects on a page-by-page basis (posts and custom post types included). For example; <code>yourwebsite.com/contact/</code> will redirect mobile devices to <code>yourmobilewebsite.com/contact/</code> instead of always redirecting to your mobile home page.
</li>
<li>
This can be overridden on any page individually with a convenient meta box adjacent to the WYSIWYG (usually underneath, by default).
</li>
<li>
Sets a cookie to remember which version of your website (desktop or mobile, usually) your visitors opted for (so it’s okay to set a link on your mobile site to view the desktop version).
</li>
<li>
Provides options to NOT redirect basic parts of WordPress: the Front page (static), Pages, the “Home” page (blog posts page), Posts, Attachments, Authors, Categories, Dates, Tags and search results.
</li>
<li>
Includes a widget for inserting a link back to your mobile site, which is only generated for mobile devices.
</li>
<li>
Includes two shortcodes for generating links to your mobile site. One is generated only for mobile devices and the other is generated regardless.
</li>
<li>
No CSS rules are used and classes are provided, yielding coders full reign to style generated links to fit the website theme. Shortcodes even allow you to set the link’s classes.
</li>
<li>
Adds a class to the <code><body></code> (<code>mobile-detected</code>) to help coders write styles specifically for mobile devices.
</li>
<li>
Leaves 404 errors untouched, allowing you to maintain 404 statuses.
</li>
</ul>
Basically, it gives you loads of control over your mobile redirects.
<h3>Custom Support</h3>
If you have a custom support need, <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=7AF7P3TFKQ2C2" rel="nofollow ugc">please purchase your support ticket here</a>. Support tickets are responded to within 24 hours, but we answer them as soon as possible.
How it works
<ol>
<li><a href="https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=7AF7P3TFKQ2C2" rel="nofollow ugc">Purchase a support ticket via PayPal</a></li>
<li>You get a chance to provide the best way to contact you and a description of your need</li>
<li>I contact you as soon as I can (no less than 24 hours) and help resolve your issue</li>
</ol>
Note: This is for custom needs for help, not problems with the plugin, or instructions that should already be explain in the description. If you feel there are important details omitted from the description, installation steps, etc. of the plugin, please report them in the Support forum. Thanks!

AddFunc Mobile Detect

Redirects mobile traffic, allows visitors to opt back, optionally prevent redirection of WordPress' parts (Post, Home, Tags, etc.)

PHP Mobile Redirect vs AddFunc Mobile Detect