I don't think so. The ATmega168 on the Arduino Mini has two extra analog inputs (for a total of 8): analog input 6 and analog input 7. These are on extra pins not found on the ATmega168 DIP package (i.e. the size and shape of microcontroller used on the normal Arduino boards) so you won't get them if you replace the ATmega8 on your Arduino NG, say, with an ATmega168.
The ATmega168 (all versions) also has three extra PWM pins (for a total of six): pins 3, 5, and 6 (the standard PWM pins are 9, 10, and 11).