This useful HOW TO has moved. Find it here: Connect Android to ad hoc wifi network
This is a really simple and completely free way to connect your Android phone or tablet to your wi-fi desktop computer or laptop. This guide can also be used to allow more than one device to connect to an ad-hoc network.
A lot of Android users would like to receive an Internet connection through their wireless network onto their device. This means that you share your computer’s Internet via wi-fi so your phone can use that instead of its own 3G. Pretty good idea to save on mobile data.