I can't say for sure that Rebook is the first to offer customizable shoes. However, their site is really intuitive and for customizable sneakers starting at $115; probably not a bad deal at all. You can:
1. Add your initials
2. Change the color of the laces, stitching, sole, base, side logo, back, overlay, outsole, sock liner, and tongue lining
Even if you decide not to purchase the shoe, the site itself is a very good example of a software service designed around a specific product.
Below is the sample shoe I created using Rebook's website:
This design costs $120. It is a combination of blue, black, and blue blink. The blue blink is the light blue used in the sockliner and customized logo in the back of the shoe.