Smule

Smule is a mix between a karaoke app and a musical video game. The app turns your Android into a real karaoke machine, and better yet, it lets you share your songs with other users.

When you register on Smule you receive one free song, although you can buy many more as you continue to use the app. It works just like you'd expect from a karaoke app: you see the lyrics on the screen and sing along to the melody you hear. It works even better if you use headphones.

One of the best parts of Smule is the social aspect, similar to social networks like Vine and Instagram. You can upload your songs to a timeline, follow other users, and be followed back.

Smule is an excellent app/game for music fans, especially for those who like singing karaoke. The selection of songs is great, and includes both well-known titles along with less popular songs.