Zebra

zebra is a recommended replacement for routed, available from the ports tree.

From /usr/ports/net/zebra/pkg-descr:

GNU Zebra is a free software (distributed under GNU Generic Public License) which manages
TCP/IP based routing protocols.

It supports BGP-4 protocol as described in RFC1771 (A Border Gateway Protocol 4) and 
RIPv1, RIPv2 and OSPFv2.

Zebra uses multithread technology under multithread supported UNIX kernels.  However it
can be run under not-multithread supported UNIX kernels.

Zebra is intended to be used as a Route Server and a Route Reflector. Zebra is not a
toolkit, it provides full routing power under a new architecture.

WWW: http://www.zebra.org/

You might also be interested in the GPL'd [Quagga], which includes zebra.

Note: you don't actually need a routing daemon for simple gateway operation; you only need a routing daemon if you have 3 or more network interfaces and you need to be able to discover the optimum interface to use to reach a given destination dynamically.

See also: gateway, Firewall, Configuring, Network Address Translation, routed