This video explanation of how to build a crate comes to mind - You can certainly include little extras and customizations, but this seems to be a rather simple approach. My team's crate has sat in storage for the past few years, and was built before I joined the team. However, I think it is fairly similar to the one shown in the video, except rather than screwing ours together, it is assembled using nails. Video here:
http://www.youtube.com/watch?v=VjANhtO_9co