There used to be little packets of colored puffed rice in the wonder bags. Just super tasty.
Something like this here: http://ecx.images-amazon.com/images/I/41UTdwDIudL.jpg
Unfortunately, I haven't seen a product like this anywhere yet, and I haven't bought Wundertüten for a long time :P
I think it would be great if these snacks were also available in Migros :)