Your mom probably warned you never to wear a short skirt to work, but you can throw that out along with the other old fashion rules. Above-the-knee hemlines are hot this season and in certain offices, they can be totally work appropriate when paired with the right tops and footwear. The key is to keep your heel low, or use tights and boots to add extra coverage below the waist. Above the waist stick to conversative necklines and a more covered-up to balance the leggier look. Of course, micro minis will never be office appropriate, at least imo, so my recommendation is to stick to a skirt cut just above the knee.