Virtual Router: I found this neat little software on codeplex for PCs running Windows 7 or Windows Server 2008 R2. With it you can share any network connection (be it over USB, LAN, Mobile Broadband etc) over wifi, and it converts your PC into a WifiHotSpot. In their own words,
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.)
And it has a very tiny memory footprint as well, and only 1 screen to make the required configuration, a damn easy user interface. I surf internet over my Reliance Mobile Broadband and/or Android Cell phone's 3G network over a USB connection. And I can neatly extend this to my wife's laptop using Wifi.