Local banks usually outdo national banks when it comes to helping their customers through rough times. People know each other and are invested in the same community. Local banks can help by choosing to renegotiate mortgages even if the government doesn't require it. This helps keep people in their homes, which benefits people and the community. If the banks can't afford to do that -- try holding a community fundraiser. Also, if the bank has a lot of people in properties they can't really afford, see if they'd be willing to switch around. Shifting some people to less expensive properties might keep the middle from falling out; then you could concentrate more on selling the now-empty top end and helping the low-end folks hunt for apartments.
Empty houses and buildings are no good for anybody. They fall apart if they're not maintained, and they depress the local economy. So, look for ways of putting them back into use as fast as possible. If one house on a block goes empty, could nearby homeowners pool funds to buy it as a neighborhood clubhouse for socializing or as space for "home" businesses? If a big store goes out of business, could the community raise enough money to buy it for a community center? An empty apartment building or other mass housing unit could become a shelter or low-income housing. All these approaches address multiple issues at once. It might be possible to raise enough money up-front to pay for them, but chances are, they're going to need bank help. See above advantages of local banks.
Most communities have one or more charities. All communities have things that need to be done, and right now, unemployment is rampant. Taking charity is bad for people if there's nothing to balance it; they wind up feeling useless. Unemployment is a huge cause of depression and isolation. Now put all these things together: An unemployed person goes to a food bank and gets a box of food. They list their practical and professional skills. Then they pick something off the list of things that need doing -- shoveling driveways for elders, babysitting children while single parents are working, driving carless people to and from appointments, tending plants in the park, etc. -- and do one in exchange for the aid received. Nobody needs to feel useless or ashamed, more stuff gets done, and people helping each other will tighten community bonds. This also lessens the need for the national government to step in and take care of people; it's not good at that.
Local professionals can also help prevent cascading personal disasters. The utility companies are often the first to see a family's budget hit the rocks. Be prepared with somewhere to send them for help, before they decide to kill each other or set the house on fire. Doctors, lawyers, and other expensive experts might allow for a certain number of discounted or pro bono cases for community members only. Sick people who can't afford treatment can make others sick; one person's legal problems can cause mayhem for others around them; and a stitch in time saves nine. If there's a crack that people are falling through, patch it! Create a local service to deal with the current problem and look for ways of solving it before it gets down to that level.
Above all: maximize use of non-cash resources. Right now there is a lot of property sitting empty and a lot of people sitting idle. Find ways to use those, rather than blowing big wads of money on poorly focused projects. Look for surpluses and reroute them where they'll do some good. Barter, trade, exchange, share, repair, improvise. Encourage people to invest their energy in the local community and reward them for doing so.
What are some other things that communities could be doing, or people could be doing on a local scale, to cope with this crisis?