WPtouch Mobile Plugin – You just can’t ignore a plugin used by more than 5.5 million blogs. WPTouch Pro is a mobile response focused suite with a full-blown WPTouch Theme, which is about faster than responsive sites with touch enhancements (ready for multi-screen), and a crisp retina interface.
The WPTouch Plugin features “Infinity Cache” to make your website blazing fast using mobile caching. Images are scaled via CSS and the plugin delivers mobile-optimized images according to the device. WPTouch uses extensions (much like add-ons within a plugin) to help render separate content for mobile devices, along with the images and faster rendition mentioned above.
WPTouch Pro : Starting at $49
They also offer a premium version available with lot more options. You can check out a detailed list of features and pricing plans.
Ideal For: Those who are looking to give a unique user experience to desktop and mobile users. This plugin has an add-on (enable server-side optimization) that allows you to supply templates specifically designed for mobile devices by detecting a mobile device is accessing your site.