It's not so hard to extract usage metrics from iPhone applications. Companies offering help with that include Flurry (disclosure: that one's partially mine), M

It's not so hard to extract usage metrics from iPhone applications. Companies offering help with that include Flurry (disclosure: that one's partially mine), Motally, Mobclix, Medialets, and Localytics. Pricing is generally free with the companies making money off of additional, primarily ad-related services. Or you can just roll your own. However, measuring conversions from marketing campaigns is still brutal, when it's possible at all - it's very difficult to buy installs profitably at volume. And the 'big killer' statement is largely accurate, although I've seen higher-priced niche applications grow more like your business did.