I've seen more and more sites doing this lately, they offer a base product and give the site visitor the ability to pick from certain options to customize their product, which are immediately reflected in a graphic of the product. The concept is like a build-a-bear for the web, or here is an example of what I'm talking about: http://www.1154lill.com/LISANET/layout.aspx?bagnbr=93
The bottom line is I want to incorporate this sort of feature into a site I'm working on, but I don't know where to get started with it. I'm not sure how to handle to image manipulation. I'm guessing ASP.NET, PHP, and/or Flash could be used; any of those would work for me to use, but where do I begin?

Any help is greatly appreciated!