The way I currently cycle I wouldn't be happy with a trailer or tagalong wheel for a child to sit on, but I'm sure I saw one once where the child seat was just in front of the handlebars above the front wheel (may have been a small front-wheeled bike, although probably not a Grifter). I'd be kind of happy with that, as we could both see what was going on, and he/she/it would be physically close to me, and more importantly I could actually see whether he/she/it had tipped over/fallen out/was drinking sneaky beers while I wasn't watching.
Does this kind of thing exist?
I've seen some ridiculous cycling with kids in trailers, and the seats above the rear wheel tend to bounce them around like they're a sack of potatoes.