migrate.rb

class CreateUsers < ActiveRecord::Migration
  def self.up
    create_table :users do |t|
      t.string    :name,                :null => false
      t.string    :email,               :null => false
      t.string    :crypted_password,    :null => false
      t.string    :password_salt,       :null => false
      t.string    :persistence_token,   :null => false
      t.string    :perishable_token,    :null => false
  
      t.integer   :login_count,         :null => false, :default => 0
      t.integer   :failed_login_count,  :null => false, :default => 0
      t.datetime  :last_request_at                                   
      t.datetime  :current_login_at                                  
      t.datetime  :last_login_at                                     
      t.string    :current_login_ip                                  
      t.string    :last_login_ip                                     

      t.timestamps
    end
  end

  def self.down
    drop_table :users
  end
end

rails_auth_tip.rb

# model:

class User < ActiveRecord::Base
  acts_as_authentic
end

# outro model:

class UserSession < Authlogic::Session::Base
end

# controller:

class UserController < ApplicationController
  before_filter :require_user, :only => :sign_out
  
  def sign_in
    @user_session = UserSession.new

    if request.post?
        @user_session = UserSession.new(params[:user_session])
        if @user_session.save
          redirect_to root_path
        end
    end
  end

  def sign_out
    current_user_session.destroy
    redirect_to root_path
  end
end

# depois pra usar nos controllers:

before_filter :require_user

template.erb.html

<!--
<% if not current_user %>
         <%= link_to "Sign in", sign_in_path %>
 <% end %>
 -->


<% form_for @user_session, :url => sign_in_path do |f| %>
        <p>
            <%= f.label :email, "Email:" %><br />
            <%= f.text_field :email %>
        </p>

        <p>
            <%= f.label :password, "Password:" %><br />
            <%= f.password_field :password %>
        </p>

        <p>
            <%= f.submit "Sign in!" %>
        </p>

        <%= f.error_messages %>
    <% end %>