There can be many a times when you cannot afford to spend those valuable $$$ to prove your concept or express yourself or give you the start you are looking for Then where do you go?? Now that open source has become such a big thing, that I don't think I need to explicitly answer this question!! But then, identifying what application to use and where can get a bit daunting (As daunting as atleast 3 rounds of googling )!! Anyways, here I would like to recommend 5 open source application which can get you rolling with your concept....