Ettercap - Ettercap is a suite for man in the middle attacks on LAN.
Connectify Hotspot - Connectify Me hotspot is a PC app that turns your computer into a Wi-Fi hotspot.
tcpdump - tcpdump is a common packet analyzer that runs under the command line.
Virtual Router Plus - Download Virtual Router Plus Windows Wifi Hotspot for free.
Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
Maryfi - Maryfi is a software program designed for laptops to start their own wireless hotspots.