We heavily depend upon social workers at the local health department to help our clients get signed up for the support they need (WIC, medical card, address any housing issues, childcare issues, etc).
Also, one of our clients is a social worker in a hospital with a level three NICU. She acts as an advocate, a specialized post partum doula of sorts, for parents who have babies there. Helping them not only with resources (housing if they are from out of town, getting things straight with insurance/medical cards, getting services set up for home for any special needs the baby might have) but also helping them deal with the red tape of the NICU. Getting parents comfortable there, helping them communicate with the staff and advocate for their baby, understanding how things work there, helping them find the resources that help them give informed consent, that sort of thing.