Here's some useful stuff i've found while building my Hackintosh:

MemtestOSX - can be run in single user mode with -s at darwin boot
Thermo - Terminal app written by our own DaemonES to report temp sensors only found in Hacks
CPUTest - GUI Glucas wrapper - Max out your cpu, test stability
MacCPUID - Intel Utility to give you info about your CPU

Please post any apps you've found!

There are a bunch of helpful OS X apps at coolosxapps.net.

I wish MACCpuid would display memory timings like the original version