How is the economy doing? Look in your underwear drawer

It looks like 2009 was a bad year for men's underwear. Mintel, a consumer research firm, says that sales of men's skivvies dropped 2.3 percent from 2008. Meanwhile, NPD Group, another firm, argues that the decline was more on the order of 12 percent. Either way, it's a fair bet that many underwear drawers are looking a bit ragged.

Some analysts refer to this economic measure as the "underwear index." While seasonal outerwear, flashy luxury clothes, and women's lingerie are often tied to seasons or holidays, men's undies tend to be pretty straightforward. They are replaced as needed, which means that their sales should remain relatively constant.