My son has been working on Flash web design interfaces for simple games over the last few years. He's gotten a pirate ship to shoot canons and lines that do something or another. However, lately he's been focused on making a web design interface to allow me to show images on t-shirts similar to my barbaric version shown here at Ekay.com and here at: free-speech.com/City1
The basic concept seems simple, but I can tell he has advanced himself in his knowledge of scripting because he no longer acts like it is easy and marvels at getting some of the seemingly simple task to work properly. I think the biggest challenge is to tie any interface back in to a shopping cart, but we won't bother to go there for now as this is just fun and games.