Website Caching with .htaccess
From http://www.limecanvas.com/speed-up-your-website-using-caching-and-htaccess/
<ifModule mod_headers.c>
# Turn on Expires and set default expires to 3 days
ExpiresActive On
ExpiresDefault A259200
# Set up caching on media files for 1 month
<filesMatch ".(ico|gif|jpg|jpeg|png|flv|pdf|swf|mov|mp3|wmv|ppt)$">
ExpiresDefault A2419200
Header append Cache-Control "public"
</filesMatch>
# Set up 2 Hour caching on commonly updated files
<filesMatch ".(xml|txt|html|js|css)$">
ExpiresDefault A7200
Header append Cache-Control "private, must-revalidate"
</filesMatch>
# Force no caching for dynamic files
<filesMatch ".(php|cgi|pl|htm)$">
ExpiresDefault A0
Header set Cache-Control "no-store, no-cache, must-revalidate, max-age=0"
Header set Pragma "no-cache"
</filesMatch>
</ifModule>