SOLVED: How can I upgrade my early 2008 24" iMac? - iMac Intel 24" EMC 2134 and 2211 - iFixit
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
Memory Upgrades for Apple iMac 2008 - Up to 6GB
Apple iMac (2008 Edition) review: Apple iMac (2008 Edition) - CNET
Memory Upgrades for Apple iMac 2008 - Up to 6GB
Memory Upgrades for Apple iMac 2011 Up to 32GB
Install memory in an iMac - Apple Support
Apple iMac 24-inch June 2008 3.06GHz Intel Core 2 Duo (MB398LL/A) | eBay