My VPS was running out of memory so I started googling to see what could be done about it. The best tip was this:

SSH into the system with putty or some other ssh utility
vi /etc/my.cnf
at the end of the section that starts with [mysqld] you want to add the following lines to turn off support for innodb and bdb.

skip-innodb
skip-bdb

restart mysql with '/etc/init.d/mysql restart'

My my.cnf happened to be in /etc/mysql/my.cnf, but after restart mysqld was using 80MB less memory! Before you do this though, make sure you don’t have any tables using innodb or bdb.