10 Crucial Days (the American Revolution in Mercer County): http://209.123.244.140/index.html
Friends of the Bordentown-Hamilton-Trenton Marsh www.marsh-friends.org 
(check out history of "White City Amusement Park" and other historical Mercer County spots in this great resource!)
Mercer County Cemeteries: http://members.cox.net/mercergen/mercercm.html  
Mercer County History Sites listing: http://resources.rootsweb.ancestry.com/USA/NJ/Mercer/ 
Mercer County Holocaust/Genocide Resource Center: www.mccc.edu/holocaust/
Mercer County Vintage Postcards (from Jack Mount): http://nostalgia.esmartkid.com/mercercards.html