With a total of 9 books either published or scheduled to be published, I thought I'd keep score of the locations where each book takes place. Below I've listed my books in the order they were written along with their US publication dates.
Fast Lane (2004): Denver, Colorado
Bad Thoughts (2007): Brookline, Cambridge and Boston.
Small Crimes (2008): fictional Bradley, Vermont
Outsourced (10/2010): numerous locations around Boston, primarily Lynn, MA and New Hampshire
Bad Karma (10/2009): Boulder, Colorado
Caretaker of Lorne Field (Summer, 2010): unnamed small New England town
Pariah (10/2009): primarily South Boston, Brighton, Newton, New York, Scotland, and especially New Hampshire
Essence (2011): New York
Killer (5/2010): primarily Waltham MA, but also Charlestown, Revere and Winthrop