app-agnostic, feature branch supporting, drop-in database.yml(based on http://www.reinteractive.net/posts/22-branch-specific-database-yml)

database.yml

<%
  app_name = Dir.getwd.split('/')[-1]
  branch = `git symbolic-ref --short HEAD 2>/dev/null`.chomp.gsub(/\W/, '_')
  db_name = branch.match(/feature/) ? "#{app_name}_#{branch}" : "#{app_name}_master"
  puts "DATABASE: #{db_name}"
%>

mysql2: &mysql2
  adapter: mysql2
  socket: /tmp/mysql.sock
  username: root
  reconnect: false
  pool: 5

postgresql: &postgresql
  adapter: postgresql
  host: localhost
  min_messages: error
  username: <%= `whoami`.strip %>

defaults: &defaults
  encoding: utf8
  password:
  <<: *<%= ENV["RAILS_DB"] || "postgresql" %>


development: &development
  database: <%= db_name %>
  <<: *defaults

staging:
  <<: *development

production:
  <<: *development

test: &test
  database: <%= db_name + "_test" %>
  <<: *defaults

cucumber:
  <<: *test