Working on the arrrrcamp website we wanted a lighter version for mobile devices. Specially when people would visit the website during the event to see the schedule or more information about a talk or a speaker.
For the mobile design I use a very common and basic iPhone CSS and HTML framework iphone universal. At first we would just tell everyone that you could visit m.arrrrcamp.be, because users could then still visit the normal website. But you can find all the information on the mobile version, so we could immediately redirect the users browsing with a mobile device to the mobile website.
A couple of weeks ago we found a nice Rack middleware that took care of this logic, Rack mobile detect. This middleware detects which device is visiting the website and adds a header to the request. Because we use a different url for the mobile design, we added a redirect options which the author also added to his version.
So just install the gem
sudo gem install rack-mobile-detect
require 'rack/mobile-detect' to your environment.
Afterwards simply add
config.middleware.use "Rack::MobileDetect", :redirect_to => '/mobile' and your mobile visitors will be redirected to the mobile version.
We did added some page caching to make it faster.