There are 3377 Paid iPad photography apps. Auto Adjust and Normalize are both in the top Paid in the less than 200 area (which is good because they actually get seen somewhere on iTunes). If the often-number-one iPhoto makes a few million a week, how much do each of the steps down make?
In the iPad rankings, you merely need to sell to be in the top 400. Period. I think 10 is enough. So while apps like Photoshop, iPhoto, and Camera+ have millions of downloads per year, once you’re out of the top 10 it’s mere hundreds a day at best.