For ebook reading I personally prefer FBReader.
For GPS, MapFactor Navigator allows you to use all free OpenStreet maps easily. The paid version works with TomTom maps. Besides that, you have all the online-only apps like Google Maps or Waze.
Note that there is no version of Garmin GPS for android (except an app pirated from a garmin-branded phone that requires rooting and modification).
OruxMaps is a powerful map reader.
For GPS, MapFactor Navigator allows you to use all free OpenStreet maps easily. The paid version works with TomTom maps. Besides that, you have all the online-only apps like Google Maps or Waze.
Note that there is no version of Garmin GPS for android (except an app pirated from a garmin-branded phone that requires rooting and modification).
OruxMaps is a powerful map reader.