Does she at least know what state she was born in? In Massachusetts, vital statistics are also kept in a centralized registry (near UMass Boston). Depending on the state and when she was born, this may not help as the older records may still exist only at the local level.

Does she have a passport? It should list the place of her birth. She might also try combing government records (e.g., social security administration) for their records under the Freedom of Information/Privacy Acts.

Can't think of anything else off the top of my head.