I have the Pis since a few month, but didn’t really do useful thing until now. And one day, I receive a new board that did not have wifi. At first I was going in the living room to share use my main rooter. But that has quickly bored me, so now I share the pi wifi connection as follow:

git clone http://github.com/Thread974/pish.git
# Might need to run ./install.sh first which will install dnsmasq

The point I like is that it is not needed to hack the raspberry pi setup to share the connection.