Don't tell the good folks at ad agency Sullivan Higdon & Sink that blasting interactive holiday cards is a waste of time and money. As with most everything in marketing, it's all in the execution. Late last month, the agency distributed an online holiday card (http://weloveholidaysweaters. wehatesheep.com) to clients, friends and colleagues. The microsite, which allowed visitors to knit their own holiday sweater and pass it along, was designed to demonstrate the agency's creativity and its, er, hostility toward sheep, which follow rather than lead—get it? According to Sullivan, Higdon & Sink, the e-card has been a hit, garnering 2,491 sweaters that people have "knitted" and submitted from throughout the country. In a testament to viral marketing, the online card was also picked up by several bloggers, including Chic Knits, Christmas Sweater Knitting, Shades of Shetland and, cue the laugh track, I Only Have Eyes for Ewe. In addition, the card was prominently placed on the Web site for ReadyMade, a magazine for creative types—not necessarily ad execs who work in the "creative" department, but people who like to make homemade peppermint marshmallows or, in this case, knit their own sweaters online. —Matthew Schwartz