I too would like more info on bench power supplies, as I find them fascinating-- or perhaps power electronics in general.
I also would like to see an episode about EMI, designing quiet circuits for electrically noisy environments, and PCB layout techniques.
Also interesting would be a show on mains power, including noise, spikes, and other AC related issues. Maybe triacs and noise produced by clipping a sine wave?
I love your show! Please, keep up the great work!