Crucial CT51264BC1067 4GB DDR3 PC3-8500 204-pin SODIMM Notebook Memory
Link: http://www.jr.com/crucial/pe/CRT_51264BC1067/
Very good, very reliable memory. Macs seem to have trouble downclocking the
faster PC3 memory, and the PC3-8500 stuff really seems to work a treat.
Very good deal on this; far cheaper than Newegg.