Residents come out and have their own swap meet! Have racks and tables available for residents to layout clothes, furniture and household items to either sell like a community garage sale or swap items with other residents. At the end of the event, whatever is remaining can be donated to a good cause such as the salvation army or a local charity.
This event goes far beyond just your average bar-b-que, but can really add a lot to your community. You can add additional fun and contests such as encouraging residents to set up their own themed selling area. Turn the event into a game where residents keep a tally on every time they make a 'swap' and whoever has the most swaps wins a small prize. Most charitable organizations will write a receipt for donations - whoever has the largest donation (based on their receipt) wins a $50 discount on the following months rent.
Have fun with this event and your residents will have fun too - everybody wins!