Things to do, not in any particular order...

- Dynamic DNS support

- SNMP support

- Asynchronous DNS support (look up names while serving other requests)

- Authentication heirarchies (particularly by MAC address or by DHCP
  Authentication Protocol key).

- Authentication protocol

- Server-to-server protocol

- Perl scripts to convert from other DHCP and BOOTP servers' config
  files to the ISC DHCPD format.

- Token ring support for bpf/nit interfaces

- FDDI support for bpf/nit interfaces

- Other network hardware support for low-level interfaces?

- Standard socket API for sending to all-ones broadcast and figuring
  out which interface a packet came in on?

- Raw socket support for single-interface machines

- IPv6/DHCPv6 support

- Dhcpd running on MacOS Open Transport

- Dhcpd running on Windows/NT

- Dhcpd running on Windows95