Envy allows you to use namespaced environment variables, simply by defining environment variables with a common prefix.
For instance, let's say you have:
EC2_ACCESS_KEY='abcdefg'
EC2_SECRET_KEY='0123456789'
CAMPFIRE_API_TOKEN='zyxwvutsr'
CAMPFIRE_SUBDOMAIN='SOULCOMPRANCER'
Envy lets you do...
require 'envy'
Envy.namespace(:ec2, :campfire)
puts CAMPFIRE
# {:api_token => 'zyxwvutsr', :subdomain => 'SOULCOMPRANCER'}
puts Envy::EC2[:access_key]
# 'abcdefg'
Envy will try to define a global constant (EC2), but will also always define a constant within the Envy module (Envy::EC2), in case some sort of conflict prevents the global constant from working properly.