Here's some of the best, both for being free and for super easy:
1. Reuse Toilet Paper Rolls: This 2008 tip from this here website is easy enough to do. Just strengthen and beautify a toilet paper or paper towel roll with some pretty paper and you won't even be able to tell this was once meant for the bathroom.
2. Reuse Ziploc Bags: I have a bad tendency to just throw away used Ziploc bags. Instead, wash out the crumbs and use this tip from Lil Blue Boo. I also love how this allows you to collect cords for one device and keep them stored in one place. You can see Ashley's step by step organizing process on her blog.
3. Broken Hair Ties: I've got a drawer full of these. The ladies and long-haired dudes know that broken hair ties happen all too often and are seriously annoying. Instead of throwing these broken elastic bands away, tie them neatly around a cord and you've got a mini bungee.