Many companies are always interested in outside interests, esp. if it involves teaching/volunteering/ community service. I would see the "moonlight-teaching" candidate as someone with a life committed to benefiting other people through education. Good for resume -- depending on the substance. (e.g., Teaching = good; Basketweaving = save it for the watercooler) It inspires an interest outside of your corporate accomplishments. And it just may put you out in front.