Developer website: Crucial.com
Crucial Mac System Scanner... Helps Mac users or administrators check a Mac with this automated software to figure out how many memory slots a Mac has, what speed they are, how much of what types of memory is installed, and what kinds and sizes of memory it will take to upgrade it. The program relays the info through the crucial.com website so you can optionally purchase the guaranteed to be correct memory from them, but no purchases are necessary to use the software just to obtain good RAM specs.
Mac OS X 10.4 or later