Apache performance tuning - Expires Headers

With the advent of YSlow, we should all now be aware of adding expires headers to our web servers. For my purposes, I wanted to enable it globally, then fine-tune per Virtual Host.
In my Apache httpd.conf, I added the following directives:

<ifmodule mod_expires.c>
<filesmatch \".(jpg|gif|png|css|js|swf|ico)$\">
ExpiresActive on
[...]

Utilizing mod_deflate & zlib for web performance

Every webmaster is looking for ways to enhance performance. I’ve researched the web and found some hits and some misses. Here are a couple changes that have dramatically improved Apache and PHP performance for me. Of course, this is my implementation, and I’d like to hear from others how I could improve.

Getting xdebug installed in OS X Tiger

Here’s what I did:
1. Install Marc Liyanage’s PHP5 package for Apache 1.3.x
2. Mod your path defaults
# sudo su -
# cd /usr/bin
# mv php php4
# mv phpize phpize4
# mv php-config php-config4
# ln -s /usr/local/php5/bin/php php
# ln -s /usr/local/php5/bin/phpize phpize
# ln -s /usr/local/php5/bin/php-config php-config
3. Get xdebug
http://www.xdebug.org/download.php
4. Install xdebug per instructions found here:
http://www.entropy.ch/phpBB2/viewtopic.php?t=847&view=next
%sudo ln -s /usr/bin/glibtoolize /usr/local/bin/llibtoolize
# [...]