Reading through the January / February 2008 issue of Cooking Light I found a wonderful article, "Dinner Day" by Jeffery Lindenmuth on Invited Your Neighbor to Dinner Day, designated since 2002 as the second Saturday in January. I had no idea. The article doesn't appear to be online, but it might be worth checking at your local library or borrowing a friend's copy (or, heck, just buying the issue) as it offers some suggestions on what to cook if you decide to celebrate.
There is an official Dinner Day website www.dinnerday.com. According to the background page:
Invite Your Neighbor to Dinner Day was born from the desire to develop a task that every American could easily accomplish. For one day out of the year, neighbors invite other not-so-familiar neighbors to have dinner with them, and eventually, friendships are formed to increase the strength of our communities. It seems simple, yet remarkably profound. These small gestures can directly influence individuals to make a difference in their own lives, while improving communities, and initiating a ripple of trust across the nation.
State Rep. Greg Vitali and then State Rep. Charles McIlhinny introduced the resolution to the house in 2002.