VirtualWiFi

VirtualWiFi is a virtualization architecture for wireless LAN (WLAN) cards. It abstracts a single WLAN card to appear as multiple virtual WLAN cards to the user. The user can then configure each virtual card to connect to a different wireless network.

Therefore, VirtualWiFi allows a user to simultaneously connect his machine to multiple wireless networks using just one WLAN card. This new functionality introduced by VirtualWiFi enables many new applications, which were not possible earlier using a single WLAN card. For example,

With VirtualWiFi, you can connect to a guest's machine or play games over an ad hoc network, while surfing the web via an infrastructure network.
You can use VirtualWiFi to connect your ad hoc network, which may contain many nodes, to the Internet using only one node.

VirtualWiFi can help make your home infrastructure network elastic by extending its access to nodes that are out of range of your home WiFi Access Point. This bundle contains:

VirtualWiFi Binaries: Contains the files required for installing VirtualWiFi. If you will not modify the VirtualWiFi software, these files are sufficient.
VirtualWiFi Source Code: Contains all the VirtualWiFi source files. If you are interested in developing software that require VirtualWiFi functionality, you should modify the source code.

Code:
http://research.microsoft.com/netres/projects/virtualwifi/software.htm