I've looked into hammocks myself, and would love to have one... the headrests in my back seat can't be used as an attachment point, so I would have to use the car seat attachment points.
I haven't seen a hammock meant to connect to the child seat attachment points, so I haven't bought one. I could hack something together, but I would rather prefer not to.
So, if someone finds a hammock that connects to those attachment points, or some hardware that makes it easy to, I'm certainly interested.
[FlatFender]: ill put it like this, if she wasnt MY aunt, id hit on her