Another I had forgotten, seems like a new book is overue, is EE Knight's
Vampire Earth series.
Just looked it up, new one in April, 10th book in the series:
http://www.amazon.com/Appalachian-Ov.../dp/0451414446
It's a post-apocalyptic series, set in the not-too-distant future after an alien race called the Kurians has taken over in the aftermath of a series of events (plagues, earthquakes, nuclear war - all orchestrated by them). They basically live on the life energy of other creatures, hence the Vampire part.