Virtual Router is a software which allows any Windows 7 computer to turn into a Wireless Hotspot (Router) and share a connection, to which others can connect via WiFi.
I can think of a few uses of such a software, apart from the obvious one of being able to have a wireless router ready in a click to when it can be used to increase the range of an already available wireless connection, like in a hall or class where the router is in one corner, the signal may be re-transmitted via Virtual Routers.
From the Author:
Virtual Router is a free, open source software based router for PCs running Windows 7 or Windows Server 2008 R2. Using Virtual Router, users can wirelessly share any internet connection (Wifi, LAN, Cable Modem, Dial-up, Cellular, etc.) with any Wifi device (Laptop, Smart Phone, iPod Touch, iPhone, Android Phone, Zune, Netbook, wireless printer, etc.) These devices connect to Virtual Router just like any other access point, and the connection is completely secured using WPA2 (the most secure wireless encryption.)
Using the software is straightforward, put in a password (at least 8 characters) and press the Start virtual Router Button. The only downside being it only works on Windows 7 (and 2008 Server) but WinXP PCs and other devices like Phones, Tablets etc can connect to the virtual server without any problem.
Virtual Router – Wifi Hot Spot for Windows 7 / 2008 R2