On Mac OS X 10.3 through 10.5, our free MemoryCell provided a quick
overview on the memory (RAM) being used by each of your applications.
Alas, it was broken by Mac OS X 10.6, and a replacement was not in the
cards. Fortunately, as Mac OS X matured, the problem of applications
using too much RAM diminished greatly.

Mac OS X 10.3: - 2.0.1
Mac OS X 10.5, 10.4: - 2.1

This is still available on
<https://rogueamoeba.com/legacy/>

Backed up for posterity

Compatibility
Architecture: PPC x64 (Intel:Mac)

OS X 10.3 - 10.5