This is a simple and cheap (>$15) addition you can make to any shower curtain to help you keep it closed when needed. This can help keep water in or just leave the shower area looking cleaner.
You can also use this same technique for any screen or sheet you have hanging to break up the space in your house.

Step 1: Equip Me(nt)

For this you will need
Magnets
Magcraft sells very strong small rare earth magnets for low prices, I bought 24 half inch magnets for $8 + $5 S/H Product NSN0640, they have a 2.5Lb pull, totaling 5Lbs. when you put two together. Id recommend something in that range as weaker magnets, that you might get at a supermarket or the like, might not have enough pull to do much. Speaking from personal experience, I threw away one shower curtain with a strip of cheap magnets that hardly kept the shower closed.

A clamp
$1 from dollar store

marker
$1dollar store again

superglue
$1 from dollar store. You might be able to tell I live down the block from Jack's, the biggest dollar store in Manhattan

Step 2: Marking the Spot

1
With your tough little fingers, pry loose two magnets from a stack and let them come together.

2
Mark the back of these magnets, this way you know which side to face them, either dot-to-dot or blank-to-blank

Step 3: Glue Thing 1

3
Find where along your shower wall you want to glue the first magnet.
Id give a couple inches from the top of the shower curtain to let it drift over to the wall , after that each should be between 5"-12" down.
Try to keep the curtain stiff as you figure on where to place the next as this will determine how big of a gap is left over between the wall and the closed curtain

4
Drop a dot of superglue onto one side of one magnet.
Make sure your drop is smaller than the diameter of the magnet itself as you'll be squishing all the good glue into the wall, and I'm sure you don't want too much on your hands.

5
Slam that sucker on the wall!
Hold in place for the proscribed amount of time, try to watch for lateral drift. Focus, dammit!

Step 4: Glue Thing 2

6
Line up your shower curtain to the first magnet and mark the curtain there.
I recommended placing the second magnet on the inside of your curtain as the curl inward will keep more water inside, where it can keep you clean, rather than outside, where it can make you fall on the ground and then bam! There you are with a compound fracture and the league game was this weekend.
...
yeah so 2nd magnet on the inside.

7
apply glue (are you doing dot-to-dot or blank-to blank?) to 2nd magnet and use the clamp to keep it there on the shower curtain. Id give it an hour.

8
repeat steps 1-7 all the way down at your discretion. I only used 3 sets for that side of my shower. I used 4 for the other side as I wanted that to be more stable.