memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load. Memcached works with a variety of languages which include:

• Perl
• Python
• Java
• C & C#
• PHP

More on memcached at: http://www.danga.com/memcached/

memcached for PHP Links:

Memcached PHP Functions: http://in.php.net/memcache
memcache Extension: http://pecl.php.net/package/memcache
memcached-client: http://phpca.cytherianage.net/memcached/

PHP tutorial with memcached extension:
Here’s a quick tutorial on how to install and use the memcached extension in PHP : Blazing speed with PHP’s memcache extension