Network String Scanner is a network discovery tool written in Perl. It allows you to search for a given string on a given port, supplied with a range of hosts. It will then determine if it has found a match.
Gobbler: A tool to audit DHCP networks
Includes DHCP rogue server detection, DHCP DoS, distributed spoofed portscanner using DHCP to obtain many source IP addresses, mulitple arp scans, filtered port detection, spoofed OS detection (nmap + port 0)