WorkCycles Fr8 family of four
A customer sent this pic along with permission to use it, thus it's not my own.
In case you're wondering: Yes, she does ride this bike with all three kids aboard, though I'm not sure exactly which positions the kids sit in. The rear carrier has a place for a second seat which they're not using.
Behind the handlebars is a little saddle with footrests.
The front carrier isn't officially a child seat, but we've seen that many people use them that way, at least for fun.