CMS 4GB (2X2GB) DDR2 5300 667MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac (Mid 2007) Pc2-5300 - A37 at Amazon.com
A-Tech for Apple 6GB Kit (1x2GB 1x4GB) DDR2 667MHz PC2-5300 200-pin SODIMM for MacBook (Late 2007, Early 2008, Early 2009), MacBook Pro (Mid 2007, Early 2008), iMac (Mid 2007) - Memory RAM Upgrade at Amazon.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
A-Tech 4GB Kit (2x2GB) RAM for Apple MacBook Pro (Late 2006), MacBook (Late 2006, Mid 2007), iMac (Late 2006), Mac mini (Mid 2007) | DDR2 667MHz PC2-5300 SODIMM 200-Pin Memory Upgrade - Newegg.com
6GB Memory for 2007-2008 MacBook Pro, MacBook, and iMac