Well, the Celeron 333 wasn't the infamous monster - it was the 300A (4.5 x 66 MHz) that could reach 450 with a mere bus switch to 100MHz and a proper mobo or at worst shorting out the B21 pin; and even then, performance improvements mainly came from overclocking the graphics accelerators of the time (like the 3dfx Voodoo or the Nvidia TnT).
As for me, I started overclocking with the Pentium 75 (mine could reach 112.5), a Cyrix P150+@133 and a Pentium 133@166 (2x83MHz and 512 Kb of L2 cache, it could kick a P200's butt). While the Cely 300A@464 I had was the biggest overclock (in proportion) I ever got for myself, I did push several (as in, 4 or 5) Sempron64 from 1.6 to 2.4 GHz without any other tinkering than raising the (cheap) mobo's reference clock and using the stock cooler; I don't doubt for a minute that, had I improved the cooling or used better mobos than bargain bin stuff and spent more time adjusting voltages, a couple of those would have reached 2.6 or 2.7.
Because yes, there was a time when owning an AMD entry-level chip was the veryh best bang for bucks you could get; I still have an Athlon II X4 620 (cheapest quad core, $99) with a base clock speed of 2.6 GHz; with a nice aftermarket cooler and a good mobo, I pushed that one to 3.4GHz stable enough in 2009 to convert DVDs and BRs all night long (I bought a NAS then and backed up all my disks). I must admit that after a week of feeling it heating up my office, I decided to retire it to the living room and replaced it with a Haswell i5 4670K. That one is disappointing though: with a factory boost speed of 3.8GHz, it just can't hold stable past 4.2 GHz. Since I don't feel like cracking the heat spreader open to cool it down more, I make do with a barely-more-than-10% overclock. Meh - still good enough for today's games.