You could make a flowering fence with these if you were so inclined.
I got the initial idea for this instructable from this one called "bottle towers". However, mine are a little different in that they are free-standing and have a wicking system
Step 1: Supplies
hot knife and/or scissors
Step 2: Notch the stake
Tie the twine to your stake so it passes through the notch to help secure it there.
Step 3: Wrap wrap wrap
This will encourage water to follow the twine down the stake to the very bottom.
Step 4: Cut doors into bottles
You can do just one side, or all four sides of the bottle, it's up to you.