Main Jahaan Rahoon - Namastey London

Playback - Rahat Fateh Ali Khan

Music - Himesh Reshammiya

Lyrics - Javed Akhtar

Simple, nice and soulful is how I would define this song.. It's got great music and is well sung too.
If you really pay attention to the lyrics - it's really sad but I think it's got to do a lot with reality.
In life, to say: The world moves with you.. but reality is you came alone, you'll go alone and while we live, we have moments and memories (yaadein) which keep us going which reminds me of a dialogue from the film Kal Ho Naa Ho which goes:

Hasso, jeeyo, khush raho
Kya pata... Kal ho naa ho..

Coming back to the song..the nice lines are:

kisi se kahoon
ke nahi kahoon yeh jo dil ki baat hai
kehne ko saath apane ek duniya chalti hai
per chhupke is dil mein tanhaayi palti hai
bas yaad saath hai teri yaad saaath hai
main jahaan rahoon
main kahin bhi hoon
teri yaad saaath hai...

There's a remix to the same song which is alright and a 'Mehfil Mix' as well which has some poetry in it. Personally like the original the best.

The film releases on the 23rd of March,'07 and here's the official site.