MySQL
Rather small site architecture.
Website stats: Webserver: Apache 2.2 Database: MySQL 5.0 APC cache for php CMS: Drupal 6.2 (bleeding-edge version)* *Aggressive caching is ON, Page Compression ON, Block Cache ON (can't use CCS),Optimize CSS/JS ON. 2 Servers: Apache/Mysql (low-tech servers - Celeron processors, 512 MB