When using a web-page that provides a service, I want it to:
- Allow me to try or taste the service without entering a username and password (or I won't it use it).
- Never supply username and password if the service is once only (or I won't use it).
- Allow me to login and use a nice administrative interface if it is a site that allows me to create content. For this, I not only accept having to supply login details; I want to be able to login.