Masha Allah – Shaykh Akram Nadwi is about to release a preface in English to his monumental work on female scholars of hadith, which currently stands at 40 volumes with biographies of over 8000 female scholars. Insha Allah this will go down in history as a major biographical dictionary similar to the ones done by the scholars of past on biographies of male and female scholars over the centuries. You can pre-order the preface and also read some notes from his talk on female scholars at the following links.
Here is also another good article on the contribution of women to hadith scholarship. http://www.islamfortoday.com/womenscholars.htm