4. Install a tap light, never stub your toe again
Materials needed: Tap light, common sense
Approximate time: Three seconds
Throw an inexpensive tap light up in a dark hallway (or closet) and never again wake up your roommates/significant other when you stub your toe and start sobbing uncontrollably. No tools required, just some batteries and common sense.
5. Hanging strips > nails
Materials needed: Hanging strips
Approximate time: One to two minutes
Use hanging strips instead of nails. Hanging strips are great tools for throwing up a couple of pictures here and there and won't leave any mess behind. Seriously, they won't even pull off the paint when you have to remove them. Peel, stick, hang, high-five.