Just do it. This is going to evolve over time. There are plenty of interesting things that serve as example for all the basic concepts of engineering. Pick something, examine it for some engineering concepts, vocabulary and look at some related applications, especially those that are imaginative and / or elegant.
The Engineering 4 Kids wiki http://engineering4kids.wikispaces.com include more than 800 entries. Some are more complete than others. One of the questions to investigate – does the section with the Engineering Design Process add to each entry. The original idea was to demonstrate the Design Process as it applied to each object. How important is this? Why? Is this of interest to the target audience – middle school kids? There are a lot of words and links. How would kids use this resource? Reference? Discovery?
The concepts and vocabulary are important as these link the underlying engineering curriculum to the objects. This should be highlighted as this be the real intent of the site – to connect objects with the “engineering” that goes into identifying needs and making an object or process to address that need.