How to backup ActiveRecord model data to YAML with ar_fixtures
First install the plugin:
script/plugin install http://github.com/mileszs/ar_fixtures/commits/master
Then dump data for all models with:
rake db:data:dump:all
There's a task for loading the data into the database, see rake -T for more information.
You can also do this without a plugin by using ActiveSupport::JSON and File.write to seed your database.