Magic Earth

Website
Google Maps alternative that claims privacy. Crowd-sourced traffic, downloadable maps for offline use, search features. I think I had to download the apk directly, or something.

Project itself is not Open Source I think, but the map database is OpenStreetMap itself.

It has interesting features, definitely not as accurate as Google Maps- but it works for the most part. Traffic isn't as good, for sure, but it's there.

A cool feature is the dashcam. When you get directions, it can turn your phone camera on and start recording for the duration of the trip. With a phone mount on your vehicle's dash, it provides a convenient dashcam solution.