Maxaud

This plugin allows you to define different CSS rules that get loaded into the page’s for specific devices.
Includes checks for 18 different tablet options and 13 different phone options.
This can be useful if you need to target specific phones or tablets to make CSS changes or show certain advertisements for certain devices.
For more options or if you feel like donating, check out the <a href="http://codecanyon.net/item/mobile-css-pro/3182318/" title="Mobile CSS Pro" rel="nofollow ugc">PRO version of Mobile CSS</a> that is available for purchase.

Mobile CSS

Allows you to define different CSS styles that get loaded for specific mobile devices.

azurecurve

Plugin providing shortcodes and functions to allow different content to be served to different types of device (Desktop, Tablet, Phone); also includes checks on types of device (iOS, iPhone, iPad, Android, Windows Phone) and mobile browsers (Chrome, Firefox, IE, Opera, WebKit).
The following shortcodes are available: 
* ismobile 
* isnotmobile 
* isphone 
* isnotphone 
* istablet 
* isnottablet 
* isios 
* isiphone 
* isipad 
* isandroid 
* iswindowsphone (alternative shortcode iswp) 
* iswindowsmobile (alternative shortcode iswinmo) 
* ischrome 
* isfirefox 
* isie 
* isopera 
* iswebkit 
* istv 
* isconsole
All shortcodes available as functions with an azc_md prefix for calling from themes, other plugins, etc. For example, is_mobile available as function azc_md_is_mobile.
Uses PHP Mobile Detect class, the lightweight PHP class for detecting mobile devices (including tablets), from http://mobiledetect.net/.
This plugin is multisite compatible.

azurecurve Mobile Detection

Plugin providing shortcodes and functions to allow different content to be served to different types of device (Desktop, Tablet, Phone); also includes …

Mobile CSS vs azurecurve Mobile Detection