There are also many about MySQL or using MySQL - here are some examples:
- How To Set Up Database Replication In MySQL
- MySQL Master Master Replication
- How To Set Up A Load-Balanced MySQL Cluster
- Running A MySQL-Based DNS Server: MyDNS
- Virtual Users And Domains With Postfix, Courier And MySQL (Fedora Core 5)
- Virtual Users And Domains With Postfix, Courier And MySQL (+ SMTP-AUTH, Quota, SpamAssassin, ClamAV)
... and more.
There's definitely a lot of stuff to play with.