Regarding your footnote...Is top 50 really the inflection point? My experience has been top 25, then top 10. I don't have the exact figures, but I had an app (finance category) get in the top 25 on around 30 daily downloads, but bounced between 11 and 13 with 100-150 daily downloads. It never did get into the top 10, or I suspect I may have been posting this from my private jet :)