I overclocked my P3-667 too
she's now a 750.
Still as slow as hell though.
Have an all SCSI Compaq P55C 233Mhz MMX. Being Compaq I think overclocking chances are slim, but a decade ago that would've been a badass machine. Still boots Windows NT Workstation 4! (although I don't know the password, cause I am dumb yo)
Got a bunch of Athlon XP's, but AMD was pretty anti-overclocking back then, and I'm too lazy for pencil mods.
Edit: and I bought a new 775 cooler so I could rebuild my old P4 and see how far I could O/C it (just for fun)....... but ........ I lost the processor
and the whores on local auction sites want more than pocket lint for them