I thought that the top app list was simply the apps that have the most downloads, but now with two apps that have been on the top 100 list I know that is not the case. My first app was in the 80's after a week. When my second app came out it hit the top 100 and past my first app on the second day, so I got all excited and thought it must have past the download count of my first app to beat it. Unfortunately that was not the case. All I know is that the second app has about twice as many downloads per day than the first app...so I guess they just rank them by downloads/day?