The ATmega8 was even used as an Arduino IC in the past, before it was upgraded to the 168 and then the 328. You should note that it has fewer timer outputs (so you cannot use PWM on as many pins) and does not support pin change interrupts on any pin, though.
The 48 belongs to the same line as the 168 and the 328, but its self-programming features are not as advanced. The 88 should be fairly compatible, though.