Theme my login  replaces the normal wordpress login and  uses modules ,it uses a sidebar widget for login

Email Settings:-New user, Retrieve Password, reset Password, user activation, user approval, user denial you can customize each of these (which accepts html )

moderation: None ,Email confirmation, Admin approved (the most secure of these is admin approved  which requires a admin to either accept or deny membership, the appropriate Email is sent )

Redirection: you can customise the page where users are sent when they login or out Can be useful for site info for users,

User Links:  Profile shows in login widget, the user can control their own settings (if you let them) you can also create your own custom links for users

For all the information you will need on customizing visit the Authors website here you will find information to customize registration forms , styling and almost everything else you may need