Simply open your wp-config file, located at the root of your WordPress install, and paste the following code in it. Once saved, WordPress will be able to use as much memory as specified.
define('WP_MEMORY_LIMIT', '96M');
Thanks to Jeff Starr for the tip! By the way, did you checked out the new version of his book Digging into WordPress?
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How to increase WordPress memory limit, the easy way