I'm referring to free registrars like .co.nr, .tk and .java-fan.com sorry about that. Can't say I ever saw .co.cc used alot though.Are you referring to actual web hosts or the free domain registrars?
As far as web hosts, 000webhost was probably the most popular free option, but it was absolute garbage.
As far as domain registrars, who could forget about .tk, .co.cc, .co.nr, and more? Those domains were everywhere like a decade ago.