Om shanti om exclusive pictures

What is common between movies like ddlj, pyaar kiya to darna kya, now recently salaam-e-ishq and soon to be released om shanti om.I think you guessed it by now that all of these movies have title taken from popular hindi songs,but in the case of om shanti om, its not just the song that has been taken from super hit movie karz starring rishi kapoor.It has been reported that story of om shanti om also deals with reincarnation like in karz