Shazam - Shazam is a mobile app that recognizes music and TV around you.
Sing! Karaoke by Smule - Karaoke with your favorite celebrity singers
SoundHound - SoundHound - the most immersive music search, discovery and play experience on mobile.
Singa - Singa is the best way to sing karaoke on mobile or tablet.
Midomi - midomi.com find and discover music and people.
iSing Karaoke - iSing Karaoke is free to use the Karaoke app that offers free access to hundreds of songs.