Well I have found 2 mystery series that I havent read and with nice strong female characters.
The first character is Anna Pigeon. As I'm sure you probably already know, Anna is a National Park Ranger and part time Detective, and every summer she works in a different National Park. This series is written by Nevada Barr.
The second character is Sister Frivisse. Someone else posted about Margaret Frazer who writes Medieval Mysteries. I love medieval mysteries. I have read most of the Brother Cadfael books.
I'm definitely going to check both these series out.