With the Schengen agreement internal immigration controls have been abolished. So even if you wanted to get a stamp when crossing say, from Germany in to France, you wouldn't be able to find someone to do this for you. At many borders the only sign that you are crossing in to a different country is that the quality of the road surface changes.
When travelling within the Schenge area by plane you also don't pass immigration normally, as Schengen passengers are routed separately from non Schengen passengers at most airport. Post 9/11 there are again identity checks when entering the departure area of an airport, but this is not immigration, those people won't be able to stamp your passport either. I can remember how in the first years of Schengen I once flew from Brussel to Barcelona without showing any piece of ID at all the whole way... That was what we as were promised then, but alas this is no longer the case.