I came across this tool called MySong from Microsoft Research team. This tool lets you produce accompaniment music for your vocals. First you have to record a song to a tempo and then the software identifies the chords and play it on piano and it sounds pretty fit for the melody! This software is still in the research phase. It might be helpful for amateur composers/musicians to explain the base tune to the person who orchestrate so that he can build upon it. Well, there seem to be other softwares doing the same service, like Band-in-a-Box.
Microsoft Research MySong
Microsoft Research MySong has given some audio samples in MySong web page and all of it sounds good. But I am not sure how this is going to work with some rhythm patterns, say for example, eastern music rhythm patterns (like the music we have here in India) or complex western/eastern rhythm patterns. So this might be worthy of having some fun for a while for the bathroom singer or the amateur singer (I don’t think professional musicians would care to spend their time at this, they would rather hire a musician to work on the different music ideas manually; there is nothing like human brains when it comes to music or other such artistic works), but would it be worthy of your money if it is released commercially? (It cannot be free, it’s Microsoft baby!) We will have to just wait and see until the final product is released.
As from what I have seen so far, it is a software that you either use for a couple of days out of enthusiasm or wanna try once and dump the next day.