Sidecar
This sidecar was built, by a company called Pryer Industries from Ada, Ohio, specifically to fit Batavus Mopeds. This is the only one that I have seen so far.

Third Wheel Basket
This was a homemade mod made by someone and sold on ebay. We're pretty sure this one is one of a kind.

Micro-moped
This appears to be a Batavus "monkey bike" similar to a Honda CT70 with small chubby tires. We have no info about this bike.