VAT Checker for EU countries is a simple PHP class to check the validity of a VAT number from the European Union countries. It provides a single function that accepts a VAT number and a 2-letter country abbreviation as input and returns a boolean value to indicate whether the number is valid.
Page Security is a small PHP class which attempts to close a couple of the security holes within default PHP configurations. Currently it will allow you to turn off all error reporting, undo gc_magic_quotes, apply a basic whitelist or blacklist to a page, and also verify the HTTP context by which a page has been called. Most of these should be considered "best practices" rather than major security vulnerabilities.
The PHP Messages class is a simple, lightweight PHP class for handling default user based messages. It has a small selection of extensible functions for warnings, errors, etc. It is very customizable, allowing for flexibility while allowing consistent looking messages to be displayed.