The SMC Barricade does it:
“Virtual Server enables WWW, FTP and other services on your LAN to be accessible to Internet users. Refer Internet Services for well known ports.
ID Service Port Server IP
1 21 192.168.123.1
2 80 192.168.123.1
3 1723 192.168.123.2
The above example provides 3 type of services: FTP Server (port 21), Web Server (port 80) and VPN Server (port 1723, PPTP).”
You can actually enable ten ports and allow you to specify translated IPs for each one of them. Believe the Linksys unit does it as well, and may do it better. Larry