Regrettably, I'm not at home, so I don't have access to my library, or the local university library down the street. However, a quick check for any ANE goddesses or gods should first be made in Black and Green's _Gods, demons, and symbols..._ (it is, I think, only a coincidence that the authors both have colors as last names...). Also, though it's now likely very old (and likely very much in German), the Reallexikon der Assyriologie will likely have an entry.

Rerettably, I cannot say off the top of my head which myths Ereshkigal appears in, though I am fairly sure that there's a connection between her and Nergal, a 'netherworld' deity.

Sorry I cannot help more at the moment, but perhaps this will get you started...

Ugula, the overseer