AMD K5 233Mhz > Pentium II 400Mhz > Katmai Pentium 3 550Mhz > Coppermine Pentium III 700Mhz > Athlon XP 1600+ 1.4Ghz > Pentium 4 1.8a 1.8Ghz@400Mhz FSB Northwood > Pentium 4 2.4b 2.4Ghz@533Mhz Northwood > Pentium 4 640 3.2Ghz 800Mhz FSB Prescott > Pentium D 920 2.8Ghz > Core 2 Duo E6600 > Core 2 Quad Q6600
I didn't really get into overclocking until the Pentium 4 640, which I ran at 4.0Ghz, the Pentium D was at 4.0Ghz, the E6600 was at 3.0Ghz, and the Q6600 is currently at 3.0Ghz. The one exception to overclocking before the Pentium 4 640 was the Coppermine P3, which got overclocked to 933Mhz.
I've owned a few other CPUs in secondary system, but my main workhorse and gaming rig history is shown above. Here are some secondary system (mainly HTPC usage) CPUs I've used.
Athlon K7 800Mhz
AMD Opteron 180 socket 939 2.4Ghz@2.6Ghz (pitiful overclocker)
Core 2 Duo E2160 1.8Ghz overclocked to 2.4Ghz
My laptop history is much easier to recall, as I haven't been a laptop owner very long and don't upgrade them nearly as much.
Amd Mobile Sempron 3600+ > Intel Pentium M 1.7Ghz