Share our Strength is a great, national food based charity for those looking to connect.
What is social capital? It's: "the network of social connections that exist between people, and theirshared values and norms of behaviour, which enable and encouragemutually advantageous social cooperation (DICTIONARY.COM)."
But in a broader sense than the literal definition, social capital speaks to the intangible, non-monetary, but still incredibly valuable 'capital' a business can build by supporting the community around it and giving back to those in need. Warby Parker is a famous, and very successful, example of a business which gives back heavily of itself by donating a pair of glasses for each pair they sell. Newman's Own is another, food based socially minded business, which gives "all profits to charity" and focuses as a non-profit.
Both of the above mentioned businesses build tremendous social values by giving to those in need with every sale they make. For restaurants, the charity model is possible on a much smaller, scaleable, and easy to manage scale. No matter your neighborhood - there are good causes which need help and support. And it doesn't have to be monetary based - literally everyone has to eat, and food donations are always appreciated. Bakeries can donate day old bread to homeless shelters. Pizza places can sponsor their local little leagues with fun pizza party fundraisers.
For higher end restaurants, sampling opportunities abound, especially in big, metropolitan areas. Almost every museum and major charity, whether arts based or social needs based, hosts a large fundraiser every year to provide vital funding for their various initiatives. Many of these fundraisers take the form of galas with a silent auction, where you can donate gift cards, but even better are those which have stations where chefs cook food in small portions for guests. The food costs for these events is usually not terribly high, and the marketing impact is very good as it brands your establishment as a socially conscious establishment whilst simultaneously showing off your goods to a large crowd of typically affluent and entertainment focused individuals. So get out in your community and look for chances to do good. It will help you connect with potential customers and make a positive impact at the same time.
