After reading a blog post about MySQL Tuning scripts I thought
about the possibility of a fully Automatic MySQL Tuner.
This is how it would work:
A daemon which would connect to your database server and then fetch status variables, just like mysqltuner and such. Then the daemon could decide that a parameter would need to be adjusted and then run "SET GLOBAL …" and write a /etc/mysql/autotuner.cf file which should be included in your my.cnf.
It should have a min/max setting for each option and some thresholds.