I first came across partitioning with release 7, when it didn't exist. Like many DBAs, I simulated it by writing a lot of application code. You can still do this – and you may have to if you haven't bought Enterprise Edition plus the partitioning option. Here's another way to do it, with partitioned views.
Proxy authentication has been around since release 9i, but it isn't widely used. It can be a very useful facility for giving certain users access to high privileges without having to give them any direct grants or roles, and avoids many of the problems of using shared accounts. It is of course fully audited.
The ability to quiesce the database was introduced in release 9, but to this day I find that many people are not aware of it. It can be really useful - so let's describe it. I'll begin by positioning the quiesce capability: when is it useful. Then detail how to do it, then reverse engineer the mechanism.