Here are some great sites about sharing food...
Mammabake (AUST)- Big batch, group dinner cooking
http://www.mamabake.com/
Mangia! Mangia! (AUST) - Rescuing their mamma's traditional recipes from extinction
http://www.mangiamangia.com.au/
Eat with me (AUST) - New ways to connect with people through shared food events http://eatwithme.net/
The Big Lunch mob (UK) - Neighbour's get together to eat
http://www.thebiglunch.com
Neighbourhood Fruit (US) - A fruit sharing/gifting program to help you locate fruit in your 'hood
http://neighborhoodfruit.com/
Shareable (US) - Not technically about food, but about all things sharing
http://shareable.net
The Stranger Dinners (US) - Kinda strange but intriguing
http://www.strangerdinner.org/
