Nielsen compiled lists of the most popular Android apps in three age groups, and the only non-Google app to crack the top five on all three lists was Facebook, which placed second among users 18 to 24, 25 to 34, and 35 to 44.

Facebook was used in the 30 days prior to the Nielsen study by 80 percent of those 18 to 24, 81 percent of the 25 to 34 group, and 77 percent of the 35 to 44 users, trailing only the Android Market, at 89 percent, 92 percent, and 95 percent, respectively.

The top five in each age group was rounded out by Google Search, Gmail, and Google Maps, in different orders for each age group. And Google-owned YouTube placed sixth across the board.