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I can't think of any series, but I really liked A Babe in Ghostland by Lisa Cach.  Maybe that one could hold you over until you find another series.

You may like the Pepper Martin series by Casey Daniels

Pepper Martin Mystery
1. Don of the Dead (2006)
2. The Chick and the Dead (2007)
3. Tombs of Endearment (2007)
4. Night of the Loving Dead (2009)
5. Dead Man Talking (2009)

Or Abby & Ophelia series by Shirley Damsgaard

Ophelia And Abby
1. Witch Way to Murder (2005)
2. Charmed to Death (2006)
3. The Trouble with Witches (2006)
4. Witch Hunt (2007)
5. The Witch Is Dead (2007)
6. The Witch's Grave (2009)

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Laurell k Hamilton  her Merry gentry books are good. and so are her Anita Blake books i think there are like 16 or 17 in them, here is the first book-Guitly  Pleasures.     and here is the first book in her Meredith Gentry books Kiss of Shadows there are 6 in that group.

kim Harrison is good also,   and I like Sherrilyn kengon I had a hard time finding her first book it is called Fantsy Lover .         hope this helps a little

Patricia Briggs werewolf series is excellent Mercy Thompson main character

Kitty series another werewolf series by Carrie Vaugn

Kelley Armstrong seriers with rotating narators, Bitten, Stolent etc

I second Kim Harrison's Rachel Morgan series quite good

Christopher Moore has some good ones, Blood sucking fiends and you suck

enjoy

I would suggest the Harper Connelly series by Charlaine Harris, not exactly a ghost series but interactions with the dead by a character hit by lightning.   very good

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These all sound like good reading! I am on a vampire kick at the moment myself but I will have to keep these authors in mind. ;-)