The following thing is the very interesting stuff which i found recently in web :)
The Connectify application will turn your Windows 7 laptop into a WiFi Hotspot to share the Internet with friends, co-workers, and mobile devices.
When it is run in "Access Point" mode, Connectify is a real WiFi Access Point running on your computer. Any device that can connect to a regular access point, can connect to a Connectify Hotspot, with no special setup or software required. When Connectify is run in "Ad Hoc" mode it sets everything up for you (Wireless card, Internet sharing, firewall, etc.) in one press of a button. It also provides advanced features like showing you what computers are connected to your network, and letting you right click them to Explore their shared drives and printers.