I'm with you Bleeck - I'll use those things in a pinch but not on a regular basis.

Battery operated socks are widely available, and you could use NiMH rechargeables in them as easily as alkalines. I don't know how you'd have a wireless power source though... I know that technology is on the horizon for computers, etc., but I don't know how it would work for heating, and anyway I would think that the main power source would have to be LOTS bigger, to the point where there wouldn't be any advantage over the rotating weight on your ankles.

There also used to be socks that came with microwaveable gel pads, just like miniature versions of the regular microwave heating pads. They aren't any bulkier than the disposables. I haven't seen them lately though so I don't know if they're still available.