Timetec 16GB KIT(4x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 Dual Rank for iMac (Late 2009 21.5-inch / 27-inch) SODIMM Memory MAC RAM Upgrade for iMac 10,1 and iMac 11,1 at Amazon.com
16GB -2x8GB Memory Ram Upgrade for 27" Apple iMac 11.1 Core i7 2.8GHz Late 2009 | eBay
iMac 27" 2.8GHz (Late 2009) | mac of all trades
How to Upgrade Memory in a Late 2009 21.5-inch or 27-inch iMac - YouTube
Memory Upgrades for Apple iMac 2009 - Up to 32GB
Can the Late 2009 27" iMac handle 32GB of RAM? | MacRumors Forums
NEMIX RAM 4GB DDR3 1067MHz / 1066MHz PC3-8500 CL7 SODIMM Memory Upgrade Compatible for Apple Mac Book, Mac Book Pro, iMac, Mac Mini (Late 2008, Early/Mid/Late 2009, Mid 2010) at Amazon.com
Apple iMac (27-Inch Late 2009) 2.66GHz Intel Core i5, 1TB HDD, 8GB Memory 885909438747 | eBay