From the JSLabs blog today there's an extremely basic debugging helper class to get you started finding that error in your code.

Debugging PHP scripts can be a difficult task, so I have written this simple php debugger class. It will display all GET and POST variables and all the properties on a currently defined object.

The code is about 20 lines long and does the most basic method of debugging - spitting out the current values of the $_GET and $_POST superglobals. It wraps it all up in a function so you can call it with one line.