Webgrind is also pretty easy to install.  But, like the previous Xdebug post, some notes for future reference don’t hurt.

On Mac OS X 10.5, I had to change the $storageDir and $profilerDir to the following:

static $storageDir = '/var/tmp';
static $profilerDir = '/var/tmp';

because I did not have permission to write to the regular /tmp folder with my particular user.  This step probably isn’t necessary for most people.