If you started right now, and spent one minute per app, eight hours a day, it would take you about two years to check out every app on the Android market. For the record, the Android app market has grown by an order of magnitude over the last two years(so, by the time you finished your minute an app two year haul, you may be looking at twenty more years...).
When looking at marketshare versus amount of available apps, apps aren't created overnight, and Android's rocket like marketshare is going to be quite a bit ahead of the development curve for a bit yet at least.