This company makes it easy for you, because you are using something as it was intended. It’s a little more difficult to think more creatively about your own waste. The next time you go to put something in the recycling bin, consider if it could be used again, repurposed. A plastic water bottle cut in half makes a great starter pot for seedlings. Old newspaper? Keep it in your camping box as fire starter! Those used Ziploc bags? Wash them out, dry, and reuse! Wrap a present in an old cracker box. Get to it! Start small by considering one reuse per week. It will become easier with practice.
Here are some ideas others have tried: http://pinterest.com/dothegreenthing/cardboard-creativity/