Crucial 4GB DDR2-667MHz (PC2-5300) CL5 ECC RDIMM DR 240-pin Server Memory CT51272AB667 at Amazon.com
Amazon.com: OWC 2GB (2 x 1GB) PC5300 DDR2 667MHz SO-DIMMs Memory Compatible with MacBook/MacBook Pro, iMac, and Mac Mini Models (OWC5300DDR2S2GP) : Everything Else
Hynix DDR2 667MHz 4GB PC2-5300P ECC SERVER Registered Memory Module at Amazon.com
Crucial 2GB Single DDR2 667MHz (PC2-5300) CL5 Fully Buffered ECC FBDIMM 240-Pin Server Memory CT25672AF667 at Amazon.com
Memory Master 2 GB (2 x 1 GB) DDR2 667MHz PC2-5300 Notebook SODIMM Memory Modules (MMN2048KD2-667) at Amazon.com