I have recently begun using the RMAN utility for backing up all of my organization's Oracle 10g databases. Previously, I've used manual OS commands and database hot backup procedures to perform the same tasks. RMAN is definitely much easier, and it brings many benefits to the table as well. While I am "old school" and still use my legacy backups in lieu of the RMAN backups (standard DBA best practices...or just paranoid), I think that if you are administering an Oracle database and not using RMAN then you are missing out.
My organization has many different databases. One in particular is used for hosting our maintenance management data. We have three instances of this database...production, development, and integration. The users are allowed to "beat up" the development instance and we can try out different features in this instance as well. Integration is a mirror of production, but we use it to apply patches and test prior to roll out on our production database. Obviously we all know what production is, so there is no need to describe that database.
Since I've begun to use RMAN, one of the best new features is the DUPLICATE database feature. This allows me to clone my production database in a matter of minutes. Previously, I had to create a database and then import a recent dump from my production database in order to acheive the same result. Now I just create the duplicate database instance, and then use RMAN to actually duplicate the datafiles, control files, and redo logs for me. It creates an exact replica (different SID and data locations of course) which allows me to easily recreate my integration instance.
Take a look at the bottom of this document for the procedures to follow in order to successfully DUPLICATE your organization's databases. It is worth the read....