This DIY photowall is a mighty fine project indeed, as is Erin's update iink here. But what if you don't fancy the linear, geometric grouping? What if you need to funk up the angles a bit, avoiding any order of inspiration whatsover?
Just toss the wire and attach the bulldog clips directly to the wall with this tutorial from Photojojo.
Given the materials, you can figure out the step-by-step.