Add a password feature for customers to the origami store application.
Add a password to the quiz show application for adding (and editing, if you have added that feature) questions. This is a situation in which different scripts in an application would require different types or levels of authentication.
Go on the Web and do research on PHP’s alternative formats for form data. (Hint: you can look up $HTTP_POST_VARS and $HTTP_GET_VARS.) Similarly, do research on ASP’s Request versus Request.Querystring versus Request.Form collections.
Go on the Web and do research on transaction support for MySQL, Access, SQL Server, Oracle, or other DBMSs.