Cyrix 133 mhz ( PR 166) I had that baby since 1997 and lasted until 2004 (ups) until I've decided to throw it away, since it wasn't good for anything.
Sempron 2800+, socket A. Crappy cpu really. I bought it because there were no more Bartons on the market and couldn't afford any Intel or A64.
Athlon64 3000+, AM2. That was a fantastic CPU, overclocked it to 2.7 ghz from 1,8 ghz. Great budget chip.
Athlon64 X2 3800+, AM2. Good cpu for its time.
Athlon64 X2 4000+ ( brisbane ), AM2. Great AMD overclocker. Managed to touch 3 ghz with it.
E7200 - fantastic chip