Technitium | Push The Limits
Technitium provides software for privacy over the Internet. Technitium MAC Address Changer (TMAC) is a freeware utility to instantly change or spoof MAC Address of any network card (NIC). Technitium Bit Chat is a secure, peer-to-peer, open source instant messenger that is designed to provide end-to-end encryption for privacy using strong cryptography.
Source: technitium.com