Personas for intranets
Although we spend most of the time talking about and using personas for public-facing sites, they are absolutely useful for intranets as well. In fact, they're even easier to create, since we sometimes have easier access to these internal users than to external customers. In addition, intranets can create turf battles even more dangerous and distracting than external sites, because everyone fights even harder for attention. This means that having actionable user knowledge in the form of personas can be even more critical for making tough decisions about what to create and how it should work.
Howard McQueen wrote a nice piece on persona-centric Intranet design that's worth a read. I'm not sure I buy into his creation process, which seems to rely too much on existing stakeholder perspectives and not enough on one-on-one primary research, but I like his idea of selecting a Persona Advocate who is responsible for keeping the personas alive within the organization.