XArp is a security application that uses advanced techniques to detect ARP based attacks. ARP attacks allow an attacker to silently eavesdrop or manipulate all your data that is sent over the network. This include documents, emails and VoiceIP conversations. ARP spoofing attacks are undetected by firewalls and operating system security features: firewalls don’t protect you against ARP based attack! XArp has been developed to target this problem: it uses advanced techniques to detect ARP attacks and thus helps you to keep your data private.
Works on Windows and Linux – more info here and you can purchase a pro version.