I'd love if it were possible to put variables into the global address space. This would be especially useful for the HTTP_*_VARS series of variables, which are pretty contention free namespace wise.

Could be a compile time option, php.ini option or something else. 

Of course, a more complete solution would be to have a 'universal' keyword which moved variables into a truly global address space, available to all functions. Not sure if this would be really desirable.