Great Voices - Rahat Fateh Ali Khan

The nephew of the Great Ustad Nusrat Fateh Ali Khan. Nusrat saab had sort of coached him as the one to carry on his lineage. The man leaves his mark on every number he sings - he ends lending a lot of credibility to the music & hence the movie.

A walkthrough of his filmi songs (Song title links are direct links to the MP3s - Courtesy fmw11):

2004
Paap - Mann Ki Lagan & Laal (Alaap)

2005
Kalyug - Jiya Dhadak Dhadak and Tujh Dekh Dekh

2006
Omkara - Naina Thagh Lenge

2007
Namastey London - Main Jahaan Rahoon - Normal , DJ Akbar Sami Remix (Ugh!!!) & Mehfil Mix (With Krishna) - The mehfil Mix has Javed Akhtar reciting poetry in addition to the voices of Rahat & Krishna.
Jhoom Barabar Jhoom - Bol Na Halke Halke (With Mahalaxmi Iyer)
Om Shanthi Om - Jag Soona Soona Lage (With Richa Sharma)
Aaja Nachle - O Re Piya

Rahat has also done vocals for Apocalypto & Four Feathers. I guess his solo album Rahat could have made a bigger impact on the world music scene i it had a better producer. Laga Rog Wachhoray Da had so much promise...

Amit Varma of India Uncut met the man himself (link)

What he did with the form of the qawaali. “Unhone ek guldasta banaaya,” says Rahat. “Usme qawwali, thumri, ghazal, muktalif kism ki musical forms ko shaamil kiya.” Nusrat made a bouquet of musical styles, but unlike what the purists say, he did not compromise while doing that. “Everthing he did retained the flavour of qawwali,” says Rahat. The essence of his music, in other words, drew from the same spiritual yearning that marks out qawwali music

Bonus:

Another great voice which will possibly remain muted thanks to the regional language lines - Hans Raj Hans
Hans Raj Hans and Rahat singing Sili Sili Aundhi Yeh Hawa.
Versions : Hans Raj Hans, Naseebo Lal & Toshi Sabri