Plugin to scale the database

If anyone's interested, I've recently released the
seamless_database_pool plugin which adds an adapter for using a master/
slave database cluster with ActiveRecord. The emphasis of the code is
to make it trivial to add to an existing Rails application. You don't
need to refactor your code or change how you use ActiveRecord. It can
also ensure consistent connections for a request to eliminate those
sinister bugs that crop up only every 1000 requests due to
synchronization delays.

If your running into issues with scaling your database you may want to
check it out.