Diagnosis tools?

I'm looking for various programs that I can put on a flash drive to be used as diagnosis tools... PC stats, monitors, troubleshooters, the like. Right now I have CPU-Z and NTFileMon on there right now, along with setup files for Firefox 2, Avast! and SpyBot. Any other ideas for things a PC Tech might have use for?

Windows Washer

system mechanic 6 is good software, i have it on all my pc's. you can download it from http://www.iolo.com