Holy crap! We've just solved one of life's great mysteries, and wanted to let you in on it. Keeping your feet warm when you cannot be bothered/are too much of a cheapskate to invest in a gadget based solution has always been a problem, but we've sussed it. Here's how: get your feet up close and personal to your PSUs. That's all there is to it. Nothing more, we promise you.
We've been doing it subconsciously for months, but now we have realized, we thought we'd let you in on the foot warming action. Unless you want your power supplies to smell like macaroni and cheese, we suggest keeping your tootsies covered/clean. (Quick tip; socks usually do a good job of covering up feet. For proof of this assertion, check out my most excellent sock, complete with fluffy poodle head, in the pic above.) Added bonus; if you have ice cold feet that are about to drop off from frost bite, they'll cool your power supplies—everyone's a winner this Christmas!