LGBT Americans wield more than $700 billion in buying power and are more likely than straight folks to spend money with companies that support them (makes sense, no?). But combing through a company's discrimination policy is no one's idea of a fun pre-shopping activity. Enter: the Human Rights Campaign (HRC).

The HRC keeps tabs on how well corporate America treats its LGBT employees, consumers, and investors. This week it synthesized data on 590 companies into an easy-to-use Buying for Equality guide, scoring companies on a scale of 0 to 100 and awarding them a rating of green (shop away!), yellow, or red. The scores are based on such criteria as whether the company provides domestic-partner benefits, bans discrimination based on sexual orientation or identification, hosts diversity training, and supports LGBT causes. And the HRC is rolling out an iPhone app early next month, so shoppers can decide whether to swing into Gap (100) or Anne Klein (45) while on the go.

Most of the HRC's scores are heartening and pretty unsurprising: 100s all around for Apple, Amazon, Google, Microsoft, and Nike. But it's the stinkers in the list that caught my eye: Cracker Barrel scored the worst of the bunch, with a paltry 15 (hashbrown casserole be damned, that number's low enough to knock them off my next road-trip itinerary). Wal-Mart and Radioshack both scored a 40, John Deere earned a 33, and Office Depot and Humana came in at 45.

Of course, a low score doesn't mean that a company is actively hostile to its LGBT workforce, whether that means only promoting straight people or encouraging homophobic remarks around the watercooler. But it does reflect a certain passivity or apathy to equality. When I spoke with Corliss Fong, VP of diversity strategies at Macy's, about her company's recent decision to officially ban discrimination against transgendered employees, she asked, "If this is what we, as a company, are already doing in practice, what argument is there to not put it in writing?" That proactive mentality earned the retailer a perfect 100--which may snag them more shoppers this holiday season.