crazijoe

Celerons (It's amazing that they still use this name even though the CPU is different.)
One must realize that Celerons are not just a PentuimX CPU with half the cache. The PentuimX uses an 8-way set associative L2 cache. The Celeron only uses a 4-way set associative L2 cache.
It wasn't untill the Tualatin core that intel included the 8-way set associative L2 cache. Tualatin core Celerons performed like full blown PIII because they were effectively full blow PIII with half the cache.
In fact there was a time Intel was shipping PIII Tualatin cores with Celeron name badge on them.

There are 8 different versions covering FSB speeds of 66MHz to 533MHz FSB.

Covington core built on the 0.35µm process
FSB speed = 66MHz
CPU speed = 266 or 300MHz
Level 2 cache = none
Core voltage = 2.8V
Package = SEPP

Mendocino core built on the 0.25µm process
FSB speed = 66MHz
CPU speed = 300, 333, 366, 400, 433, 466, 500, 533MHz FSB (the 300 was labled 300A)
Level 2 cache = 128KB full speed
Core voltage = 2.8V
Package = 300-433MHz SEPP / 466-533MHz socket 370 PPGA

Coppermine-128 core built on the 0.18µm process
FSB speed = 66 or 100MHz
CPU speed @ 66MHz FSB = 566, 600, 633, 666, 700, 733, 766MHz
CPU speed @ 100MHz FSB = 800, 850, 900, 950, 100, 1100MHz
Level 2 cache = 128KB full speed
Core voltage = 66MHz FSB 1.5v / 100MHz FSB 1.7v
Package = socket 370 FCPGA

Tualatin core built on the 0.13µm process
FSB speed = 100MHz
CPU speed = 1000, 1100, 1200, 1300, 1400MHz (1000 and 1100 were given an "a" extension to differentiate them from the coppermine.
Level 2 cache = 256KB
Core voltage = 1.45v
Package = socket 370 FCPGA2

Williamette-128 core built on the 0.18µm process
FSB speed = 400MHz
CPU speed = 1.7 or 1.8GHz
Level 2 cache = 128KB
Core voltage = 1.7v (SL7RU stepping is 1.5v)
Package = socket 478

Northwood-128 core built on the 0.13µm process
FSB speed = 400MHz
CPU speed = 2.0, 2.2 , 2.3, 2.4, 2.5, 2.7, 2.8GHz
Level 2 cache = 128KB
Core voltage 1.25-1.75v
Package = socket 478

Prescott-256 core AKA Celeron D built on the 90nm and 65nm process
FSB speed = 533MHz
CPU speed = 2.13, 2.26, 2.4, 2.53, 2.66, 2.8, 2.93, 3.06, 3.2GHz
Level 2 cache = 256KB
Core voltage = 1.25v - 1.4v
Package = socket 478 and LGA775 (socket T)

Cedar Mill-512 core AKA Celeron D built on the 65nm process
FSB speed = 533MHz FSB
CPU speed = 3.2 or 3.33 GHz
Level 2 cache = 512KB
Core voltage = 1.25-1.4v
Package = LGA775 (socket T)

This only covers the desktop versions. There are still mobile Celerons and Pentiums.