Is there anyone still interested in bringing NetBSD to the desktop?
It's already there, but I think I get your point.
My "lightweight" desktop OS of choice on older hardware is grudgingly Lubuntu. I'm not a fan of Linux, but in this case it's pretty snappy and apt-get works well. I install this on a USB stick and carry it around with me.
If someone could build a live CD or light install that resembled Lubuntu and had pkgin setup out of the box, I would be happy.
My #1 concern for newer users is easy connectivity with wifi. I haven't seen a nice gui for wifi connectivity lately. If it exists, I need to check it out...