Fantastic Fiction
http://www.fantasticfiction.co.uk has a 'Visitors to this page also looked at these authors' box at the bottom of every author page.
I looked at Ms. Evanovich's page; in addition to the authors already mentioned in this thread and on that site, I suggest J A Jance.
Good luck!
BTW, Nora Roberts is J D Robb. Roberts is used for her romance books and Robb is for her mysteries.