From this new post today on frak's blog, there's a look at a PHP debugger that makes it simple to debugg your PHP applications - GUBED.
To run the debugger, you call some PHP scripts (also installed on the same website) that grab the code of the web page you want to debug, and call you back (as other 'hard server install' solutions do).
I never realised there was such a thing! The name of this great program is GUBED (debug backwards) and it is based on a really simple idea.
Gubed is a cross platform program to debug PHP scripts. For a general overview, see the About section, for a more technical description, see the documentation.