Task.find(:all,
          :select => "distinct tasks.*",
          :joins => "inner join users on tasks.user_id = users.id inner join time_entries on time_entries.task_id = tasks.id",
          :conditions => ["users.id = ? and time_entries.task_date >= ? and time_entries.task_date <= ?",
                          @user.id,
                          '2007-06-18',
                          '2007-06-24']).map{|t| t.project.name}

## could that be rewritten like so?

class User
  has_many :time_entries, :through => :tasks
end

@user.time_entries.find_all_by_task_date(Date(2007,6,18)..Date(2007,6,24)).map{|t| t.project.name }