Feel free to add your own how-to and categorize it in this list.

• Automatically generate password for users (simpler registration)
• Change the default sign_in and sign_out routes
• Customize routes to user registration pages
• Redirect to a specific page on successful sign in out
• Customize the redirect after a user edits their profile
• Customize the redirect path after destroying a session (signing out)
• Override confirmations so users can pick their own passwords as part of confirmation activation
• Redirect with locale after authentication failure
• Require admin to activate account before sign_in
• Set up devise as a single user system
• Two step confirmation
• Redirect back to current page after sign in, sign out, sign up, update
• Redirect from HTTPS to HTTP on successful sign out
• Redirect to a specific page after a successful sign in or sign out
• Redirect to a specific page on successful sign in
• Redirect to a specific page on successful sign in and sign out
• Redirect to a specific page on successful sign in or sign out
• Redirect to a specific page on successful sign in out
• Redirect to a specific page on successful sign up (registration)
• Redirect to a specific page when the user can not be authenticated
• Do not redirect to login page after session timeout
• Create a guest user
• Allow users to edit their password
• Require authentication for all pages and avoid "You need to sign in..." message when hitting the application root
• Use a custom email validator with Devise

• Create custom layouts
• Custom mailer
• I18n
• Set :host and :port for all devise mailer urls
• Override devise_error_messages! for use in views

• Allow users to sign in with something other than their email address
• Authenticate via LDAP
• Create a guest user
• [Email-only sign-up](https://github.com/plataformatec/devise/wiki/How To: Email-only sign-up)
• Edit an account without providing a password
• HTTP Authentication
• HTTP Auth Basic
• Isolate users to log into a single subdomain
• Recaptcha
• Remote authentication with Devise
• Set up devise as a single user system
• Sign in using either a username or email address
• Simple Token Authentication Example
• Use case insensitive emails
• [Use SSL (HTTPS)](https://github.com/plataformatec/devise/wiki/How-To:-Use-SSL-(HTTPS)
• Use subdomains

• OmniAuth: Overview
• OmniAuth: Testing
• Omniauthable, sign out action and rememberable

• Capybara
• [Controllers tests with Rails 3 (and rspec)](https://github.com/plataformatec/devise/wiki/How-To:-Controllers-tests-with-Rails-3-(and-rspec\))
• Cucumber
• OmniAuth: Testing
• Rspec with devise and machinist
• Speed up your unit tests
• Stub authentication in controller specs

• Add an Admin role
• Add a default role to a User
• Create a guest user
• Integrate with CanCan for roles management
• [Manage Users with an Admin Role (CanCan method)](https://github.com/plataformatec/devise/wiki/How-To:-Manage-Users-with-an-Admin-Role-(CanCan-method)
• Require admin to activate account before sign_in
• Sign in as another user if you are an admin
• Turn off trackable for admin users

• Add :confirmable to Users
• Create a custom encryptor
• Create Haml and Slim Views
• Configure a master password
• Customize user account status validation when logging in
• Disable user from destroying his account
• Disallow previously used passwords
• Dynamic user registration timeout
• Embed users in your account model with Mongoid
• Protect Resque Web with Devise
• Send emails from subdomains
• Send emails in background (Resque, Sidekiq and Delayed::Job)
• Using paranoid mode, avoid user enumeration on registerable
• Use Devise Inside a Mountable Engine

• Add sign_in, sign_out, and sign_up links to your layout template
• Display a custom sign_in form anywhere in your app
• Sign in from a controller
• Use Devise generated method and filters for controllers
• Find a user when you have their credentials
• [Make Devise work with other formats like mobile, iphone and ipad (Rails specific)](https://github.com/plataformatec/devise/wiki/How-To:-Make-Devise-work-with-other-formats-like-mobile,-iphone-and-ipad-(Rails-specific)
• Manage users through a CRUD interface
• Mass password reset and email notification

• Use with BackboneJS models

• List of Devise Controllers

• Upgrade to Devise 2.2
• Upgrade to Devise 2.1
• Upgrade to Devise 2.0
• Upgrade to Devise 2.0 migration schema style
• Migration legacy database

• Migrate from restful_authentication to Devise
• Add devise required columns to an existing users table
• Change an already existing table to add devise required columns