I just had a somewhat hard time to install rmagick on a new Ubuntu 14.04 server. The first thing I realized was that the necessary packages to compile rmagick are now

apt-get install libmagickcore-dev 
apt-get install libmagickwand-dev 
apt-get install imagemagick

After I had everything set up, I had this strange error in my apache logs

App 2599 stderr:
App 2599 stderr: ActionView::TemplateError (uninitialized constant Magick::MaxRGB) on line #12 of app/views/recipes/search.html.erb:
App 2599 stderr: 9: <% if @recipes.size > 0 -%>
App 2599 stderr: 10:   <% if @is_cat_search -%>
App 2599 stderr: 11:     <%# Special case, we searched for all recipes in a category -> display the
App 2599 stderr: 12:     title %>
App 2599 stderr: 13:     <%= titlePic @cats.name, false %>

apparently Magick::MaxRGB doesnt exist in the newest rmagick version. Using

gem install -v=2.13.1 rmagick

solved the problem for me