Fossdroid is the best way to find FOSS apps. The interface is very sleek and highly usable, and as gorgeous as the Google Play Store or the iPhone app store.
On the Google Play Store and in other places where android apps are announced, it’s difficult to sort out which of the apps and games are free/open source. Highlighted right on the front page of Fossdroid are apps such as AdAway, Firefox, VLC media player, K-9 Mail and TD (a way to watch Twitch video streams).
Fossdroid assigns a separate page for each app and it contains a description, download count and links to the main site. It has a comment section powered by Disqus which gives any user the ability to review the app. The major thing missing are preview screenshots of the app which is something that I love about the Google Play Store, especially when there are screenshots showing how the app looks on both tablet and phone. Fossdroid’s comment section is empty for most apps as the dominant app rating and reviews still happen on Google Play Store. If they could find a nice way to include the overall ratings from Google Play Store or have their own rating system, it would be much nicer.
In any case, if you’re looking for a nice simple way to find Free/Open Source apps for your Android phone or tablet, try out Fossdroid.
There is also an app for Android called F-Droid which lets you search for free/open source apps on your phone and directly download them and keep them up to date.