The Bakfietsen have been making some waves in Portland, but a mere 100 miles to the south are two very worthy bicycle manufacturers we should keep in mind.
The Center for Appropriate Transport in Eugene has several of what they call human powered machines (HPMs) of different types and configurations. The one that came to mind first when I saw a picture of a Bakfiets is this one.
There’s also Bike Friday, which makes custom-fitted folding bikes, including modular tandem and three-seater bicycles. There was a bicycle taxi service on campus that used two and three seater bikes when I was a student at University of Oregon. I don’t know if the taxu service is still in existence, but the folks who made their bikes still are.