Here's an iPad metric that you might not be looking at: Bible app sales.
Monday, a Bible cracked the top 10 highest-grossing book applications for the iPad for the first time, according to Drew Haninger, CEO of the scripture app's publisher, Olive Tree.
The theory of the case here is that if Bible applications continue creeping up the sales rankings, we can infer that the demographics of the iPad are broadening out from what we assume is an urban, liberal, fairly areligious base.
The Bible, of course, is a mainstay iPhone book application, and easily the most popular book in the history of the world. On the Kindle, which probably has the broadest range of eReader users, the Bible ranked 50 in their list of best-sellers at the time of publication.
Olive Tree's NIV Bible BibleReader is the highest-grossing iPhone Bible app right now, too, ranked second in books just behind Green Eggs and Ham. Between the iPhone and iPad, including free versions, Haninger said his company is getting 3,000 downloads a day. The iBible may not exactly be iBeer in its heyday, but sales on the iPad are growing, Haninger said, as the device has passed 3.5 million units sold. (Atlantic colleague Eleanor Barkhorn also pointed out to me that the NIV is considered to be the more "conservative" Bible translation and less likely to be used at more liberal mainline churches.)
The rest of the top-selling book applications also suggest that the iPad isn't solely being purchased by young guys with cash to burn. The paid app list is dominated by Toy Story and Dr. Seuss titles! Anecdotally, parents seem to love the iPad for the child pacification magic tricks it can perform. A study by the consumer research firm, MyType, found that parents were more likely than non-parents to own an iPad.
There are a couple of strong counterarguments against the Bible app as demographic probe. First, books are a tiny slice of the overall app market. Even the best selling book apps aren't in the top 100 apps overall. Second, book sales are messy because books can be purchased for the iPad in a variety of ways, most prominently through the Apple's iBooks and Amazon's Kindle applications. So, caveat lector, we're looking at incomplete and only suggestive data.
Still, book (and Good Book) application sales are interesting because the heavy-duty game and joke app purchasers get screened out. Perhaps they allow us to have a more complete picture of who iPad users are, beyond just "selfish elites."