It would be great to have a possibility to track memory leaks.
I know I can track functions' and method's memory usage like it's written here http://derickrethans.nl/xdebug-and-tracing-memory-usage.html, but it won't help in some situations.
Sometimes I need to see how much memory PHP occupies after method finishes and after PHP removed all local variables from memory to detect memory leaks. Currently xdebug tracks memory usage before Zend engine removes locals.