Hi, and sorry for my bad English 
I'm currently dismantling an old sattelitetuner, and I think maybee I have struck gold 
inside it it found an ATmega8 microcontroller. Is there any resemblance to the ATmega chip in the arduino?
Can it be used for something usefull?
Did fint some ethernet controller and a powerpc processor, but those are SMD, and that is not my strong side.
Yes you can use this to make an arduino type board:-
http://www.arduino.cc/playground/Learning/AtmegaStandalone
The Arduino NG and older models had an ATmega8 processor. You might be able to re-FLASH the ATmega with an Arduino bootloader and use it in a bare-bones Arduino clone. It is possible that serial programming has been disabled on the chip or the system clock is set strangely. You may need to provde a clock signal and/or use a High Voltage programmer to get it reset to work as an Arduino.
An old STB with powerpc cpu? Looks like a dreambox or a dbox2.
They are cool machines,I have a few at home still in active duty.
Yeah, it's a Dreambox BM7000-s, but since the powersupply is dead and i dont have a sattelite dish any more i figured i'd dismanltle the poor thing
I'm not really into SMD stuff yet, but i'm saving the components just in case 
Is it possible to just rip out any at atmel/atmega microcontroller and reprogram it?
I currently have these;
2stk atmega 103
5stk atmel AT90S8515
and a few others that i dont have in front of me..
I work as an elektrician/phone repair man?(not shure what the Enligh term is) and i have access to alot of "old" devices with these sort of microcontrollers in them. Would be fun if i could make use of them all