MOBIFY is a service that lets you create a mobile version of your site for free. You start by entering your site url, and selecting regions of your page design to be used in the mobile template, using their online template editor. For many sites, one template may be sufficient to serve all of your page types. After selecting regions, you may change their order in preview mode, as well as add custom HTML and modify CSS. Custom domains are supported, and with an upgrade, you may remove the Mobify branding and receive web analytics. You can use it with a plugin for your CMS, or by simply inserting Javascript into your site, which redirects to the mobile version.
I've tried several mobile services in the past. This one is perhaps the easiest I've had the experience of setting up. The initial setup time was maybe 15 minutes, plus the time to wait for the CNAME to update on my webhost. You can try Konigi mobile at m.konigi.com, or view konigi.com on a mobile device.