Standing Separate Head to Knee Pose: When I first began yoga, I noticed how my feets were stretched in ways they hadn't been before while realizing how much in need of a stretch they actually were. Just as my shoulders gained tension through the combination of stress and poor posture, I learned my feet had also built up a sense of tension... probably in their attempt to consistently remain in a pair of flimsy flip-flops. But as bad as flip-flops are for your feet, I couldn't imagine how my feet would feel in heels (basically, I couldn't imagine dressing like an adult). And while I've heard skepticism as to the existence of metal health issues or have seen such skepticism in the Senate health care bill, it's amazing that the first thing we seek to relax after a long day is our minds. But our feet deserve some love too. Below is a video of standing head to knee which will stretch (among other things) the top of ya feets.
Awkward Pose: I'm inherently awkward which perhaps gives me a leg up in awkward pose (once joked my yoga instructor). While the top two poses work to stretch the top of your feet, the second part of awkward pose works to stretch the bottom of them. Standing tall on the toes, one bends the knees and lowers their bottom until it appears they're sitting in an invisible chair. While it's common for the legs to wobble, they'll also develop a fair amount of muscle from the pose.
So there you have it, a few way to stretch ya feets. And as you take care to relax the muscles and ligaments in the region, you'll find yourself taking care to make sure they're not tense throughout the day... eventually leading to a lessened need for stretching and more time for happy hour. ;)