I decided to try my hand at making a modernized version of the 1920's "lamp socket aerial". It consists of a pair of .001uF, 3 kilovolt capacitors (overkill, I know, but it's what I had), each one soldered to a separate lead of a cheap extension cord with one end cut off, with a pair of "binding posts" made of hardware store 8-32 brass screws, nuts, washers, and thumb nuts, all mounted inside an old pill-bottle with a child-resistant cap (keeps my kids out of it). All leads were carefully insulated with heat-shrink tubing to prevent accidental shorts:
It works surprisingly well! With the binding posts just connected to the antenna and ground posts of my Atwater Kent Model 40, performance is no worse than using a wire strung up around my room near the ceiling, and actually a bit more quiet. Adding a ground wire to mains ground (my only grounding option at present) made things much noisier due to increased RFI, but also increased sensitivity many times over to the point where I was able to pick up a station that I was never able to pick up on this set before.