Soulless, by Gail Carriger
This is a totally charming, extremely entertaining steampunk supernatural romance/comedy of manners. Vampires, werewolves, and ghosts are all part of English high society, and indeed are responsible for a great many of the advancements made in this alternate history. Alexia Tarabotti, born both without a soul and to an Italian father, finds herself more and more embroiled in the mysterious disappearances of supernatural entities after she accidentally kills a vampire.
The characters were colorful and fun (there is a particular fabulous vampire that I totally adored), and I found myself actually rooting for the main couple. I don't read romance very often, but I enjoyed this quite a lot.
Gail Carriger's website.