This tutorial explains how you can configure Apache2 to set the Expires HTTP header and the max-age directive of the Cache-Control HTTP header of static files (such as images, CSS and Javascript files) to a date in the future so that these files will be cached by your visitors' browsers. This saves bandwidth and makes your web site appear faster (if a user visits your site for a second time, static files will be fetched from the browser cache). This tutorial was written for Debian Squeeze.

This tutorial describes how you can host multiple SSL-encrypted web sites (HTTPS) on one IP address with Apache 2.2 and GnuTLS on a Debian Lenny server.

http://www.howtoforge.com/hosting-multiple-ssl-web-sites-on-one-ip-address-with-apache-2.2-and-gnutls-debian-lenny

Varnish is an open source "web accelerator" which you can use to speed up your website. It can cache certain static elements, such as images or javascript but you can also use it for other purposes such as Loadbalancing or some additional security. In this tutorial we will focus on the latter one. In this mode, Varnish will stop incomplete HTTP requests from reaching your Apache webserver.

http://www.howtoforge.com/putting-varnish-in-front-of-apache-on-ubuntu-debian

This article explains how you can cache your web site contents with Apache's mod_cache on Debian Lenny. If you have a high-traffic dynamic web site that generates lots of database queries on each request, you can decrease the server load dramatically by caching your content for a few minutes or more (that depends on how often you update your content).

http://www.howtoforge.com/caching-with-apaches-mod_cache-on-debian-lenny

SphinX is a great full-text search engine for MySQL. Installing the Sphinx daemon was straightforward as you can compile it from the source or use a .DEB/.RPM package but SphinxSE was a little bit tricky since it needed to be installed as a plugin on a running MySQL server. So if you use Debian or Centos and install your MySQL from a .deb or .rpm package this is how you do it.

http://www.howtoforge.com/sphinx-as-mysql-storage-engine-sphinxse