You’ve probably heard of the “lipstick index”-the theory that lipstick sales rise when the economy tanks. Well, it’s time to start paying attention to what The New York Times┬ácalls the”lacquer index.” Yes, nail polish seems to have bumped lipstick aside as this economy’s growth industry. The Times reports sales of department store nail polish brands rose 67 percent in 2011 compared to the previous year, while mass market brands’ sales rose by 29 percent in the same time period, according to NPD Group.

What’s behind the trend? It doesn’t hurt that pop stars and fashion designers are launching their own nail polish brands or lending their names to existing brands. A raft of innovations, ranging from glitter, stick-on patterns and scent to holographic images, crackle surface treatments and nail art, has expanded the options available. And customers seeking to save money are clamoring for DIY innovations like at-home gel manicure kits.

Nail polish offers a cheap thrill-one that’s not confined to trendy teens. Even the most conservative banker might sport cheetah-print or acid green toenails hidden under her pumps-and probably is, given the surging popularity of odd colors and crazy prints.

The latest group going gaga for mani-pedis? According to The New York Post, it’s men-and not the usual metrosexual suspects. Recent photos of Jets QB Tim Tebow and Nets forward Kris Humprhies getting pedicures might help bring nail care out of the closet for the average dude. In New York City, Bliss Spas reports those asking for its “manly-cure” rose by 10 percent this quarter compared to last year, and nail salon Tenoverten says men account for 10 percent of its clientele.

Does the trend toward “man”-icures have legs outside Manhattan? I’m not sure, but smart entrepreneurs would do well to be prepared.