One of my all time favorite Mac applications, the great Mactracker, has reached version 4. Macktracker provides all the information you'd ever want on every Apple, Newton, iPod, Airport Basestation, Motorola, PowerComputing, and UMAX Mac OS computer ever made. Quickly find processor speed, memory type and capacity, supported Mac OS versions and a whole lot more.
Changes in version 4 include smart categories and independent database updating. There's even an iPod version that travels with you. Mactracker 4 is free and requires Mac OS 8.5-9.2.2, Mac OS X 10.2 or later. If you've got a basement full of vintage Macs (like I do), this is a must have.