I'm sure you have all seen the post on Cycle Mumbreeze that shows bicycle child seats in the wild in Kawasaki, Japan. No? Go look right now. They're so. dang. cute!
See? Super cute. Via "Nemo's great uncle" on Flikr,
under Creative Commons Attribution-NonCommercial-ShareAlike 2.0 license.
I have found a source that ships internationally for the white metal basket seat in the Cycle Mumbreeze post: Bicycle Hero. They also sell through their eBay store. The cost is about C$70 (including free shipping), and it comes with a three-point harness instead of just a lap belt - both wins over the Bobike option I was considering, IF it works. I also really like the big mesh leg protectors. We'll see how well it works for Dom when it arrives... it may get quickly inherited by Angel's toddler if he won't fit. =)
Meanwhile, here are some more Flikr photos of it in use, mostly showing only lap belts attached. It looks like it attaches to any rear rack, and like it ought to be big enough for my little guy... cross your fingers for me!