getting one column or method from AR find

for a current project i'm working on, there are certain actions which trigger emails to be sent out to users.

currently i'm using something like users = User.find(:all, :conditions => '....')

and then looping through all of the users in the collection and adding their email address to an array.

i'm sure there has got to be an easier way to extract just that column of information to either a hash or any array right?