[ce4]

I'm also a huge fan of OsmAnd, it has many outstanding/unique features that other map solutions neglect to offer (albeit some features are a bit hidden).

    In no particular order, things that I like:
    - Wikipedia (offline). Discover articles by location
    - Topographic maps (nice for hiking)
    - speed camera warnings
    - completely free & open source
    - you can alter the options, add your own POIs, etc.
    - draw tools, use polylines to measure distances
    - find any POI by name, category or location (they're *all* indexed)
    - copy a position's latitude/longitude to the clipboard
    - start route from a distant starting point (instead of current location)
    - discover opening hours of shops/etc.
    - launch calls from a POI's attached contact number
    - public transport (nice for city trips)
    - GPX logging
    - tools to support OpenStreetMap editing
    - route along saved .gpx/.kml track
    - ...

While it had been available exclusively for Android for a long time, there's now an iOS version as well.

EDIT: Formatting

PS: In the past I've even gone so far as to add phone numbers to my favourite pizza deliveries on OpenStreetMap to be able to call them using OsmAnd.