An Acronym with several meanings:

Revolutions Per Minute
The standard measure for the speed of spinning mechanical parts, such as the the media in HardDisks.
RPM Package Manager

Initially RedHat Package Manager, later changed to a RecursiveAcronym.

A Package format invented by RedHat but also used by SUSE, Mandriva and others. Also the name of the PackageManagementTool written by RedHat to use this format. There are now frontends like AptForRpm and Yum (recommended for FedoraCore) that wrap RPM to solve what has become known as RPM Hell (or dependency hell).

See RPMFind and FreshRpms for source or binary RPMs for many distros. The latter also has APM repositories.