Examples of successful efforts to preserve multi-unit buildings with rents affordable to low-income residents. 

Some examples of some less common living arrangements, and one example of a less common working arrangement.

The way these programs are designed, the majority of the funds go to those who don't have the greatest need.

This pretty impressive web tool from the Urban Institute shows how difficult it is to make larger affordable housing projects pencil out. 

Much of the country still allows landlords to discriminate against low-income potential renters based on the source of their income

It is, in general, cheaper to build on open land than to attempt to build infill in an existing neighborhood.  Can you build infill in a reasonable way, and have it pencil out? 

New analysis of American Community Survey data shows that, despite more resistance to sprawl due to commute times and environmental impact, cities have not found effective ways to ensure compact development, with the majority of new residential construction being at very low densities.