Xarina Input Validation
Xarina Input Validation is a small set of scripts which can be used to create with a single line of code in your php application you can recieve a variable either from a GET or POST (or both), set a default variable, clean the input from nasty folks, and set exactly what you are looking for. The validation scheme was originally created for Xaraya and further details can be found there.
Support and Discussion can be found on the Xaraya Discussion Boards.
To use with your application, simply include / require xarVar.php or place xarVar.php and subsequent validation schemes into your include path. An X-Ref of the script can be found at http://wyome.com/xar-val-xref.