i still have several atmega8 chips and only few arduino v2 left.
on which board can i use atmega8?
not diecemila, i suppose?
is there someone around still selling boards using atmega8?

You should be able to replace the ATmega168 with a ATmega8 on any Arduino board with a removable microcontroller, including the Diecimila. You'll still want to select "Arduino NG or older w/ ATmega8" from the Tools > Boards menu.