Pinch Media, which is among the early movers in providing analytics on the iPhone platform, has shifted its focus somewhat, CEO Greg Yardley told me at last week's Mobilize conference.

While the company started out helping developers with advertising, the New York-based startup is now focusing on analytics.

The reason is simple: "the iPhone is a really rich monetization platform... You can make the most money by selling your application," Yardley says.

But with more than 3,500 apps and counting, the platform is "getting crowded," which means it's easy to get lost in the pile.

The key is getting on the lists of best-selling apps, says Yardley, who's been closely watching the platform develop.

One of the company's clients that made it to the No. 2 position was making "thousands of dollars per day." 

That's backed up by what we heard from Steve Demeter, developer of Trism, who says he's been making big money on the iPhone platform.  

Based on Pinch Media data, an app that lands on the Top 100 list can expect to double its sales, and landing on the Top 10 has an even bigger impact.

The Top 100 list at any one time is largely based on one-day sales -- "it's a rolling 24-hour period" -- so the key is "to try to generate a lot of sales in a short period of time," he says.