Musixmatch is great must have app for all music lovers out there and I am sure you will sing along.
They claim to have world’s largest database of lyrics More than 7 mln lyrics in 30 languages and yes Hindi songs are also listed. Currently the #1 Lyrics Music Player on Google Play.
This app get’s automatically SYNCHRONIZED with your music library and display lyrics as the song is played on your phone or desktop. (See the video down)
Currently this app is supported on mobile phone of Android, Iphone and Windows Phone 7, You can also download it for windows 8 desktop and for your MAC from http://www.musixmatch.com/
Is it legal ? Of-Course it is legal, They have worldwide licensing with all the major music publishers for worldwide commercial rights of lyrics. So just download this application and Sing anytime, anywhere, With your friends and family.
To download this application on your android based phone. Goto google play >> search for musixmatch and click on download and its done ;-).