NetBSD is known for its portability and running on the most architectures and having support for old and obscure hardware. However, it doesn't get hype in other areas it's strong in.
It is a secure OS, and whenever holes in software are found they're quickly patched. It stays on the cutting edge of IPv6 development, also. Not to mention its ports system can run on other operating systems (e.g. Darwin, Solaris, and Linux).
NetBSD works as great for servers, routers, embedded systems, and workstations.