It's been quite a while that I searched for this solution. I needed that desperately. Because now a days, websites use gradients, sharp quality images and curves. Now when there are a lot of backgrounds and gradients in webpage then how we will manage the html data and images floating over these, specially in the case when these top guys have their own backgrounds and curves etc.
You will use *gif images for clear white spaces. Ok but sometimes doesn't matter how much you try, you can't get a crystal clear quality gif image with curves and corners. Not unless you are a wizard. Now PNG images have transparent background and we can put PNG images in websites. But PNGs show a default greyish background where it is transparent, unless you treat it right with some javascript code.
I have two solutions for PNG transparency issue.
One is simple and covers problem of images present in html but not through css and backgrounds.
Second one covers background and all img tags
http://www.techmynd.com/png-image-trans ... d-example/
http://www.techmynd.com/transparent-png ... -download/