I have used thumbtacks... but I'm too anal-retentive to tolerate the hole in my posters.
Then I moved on to sticky tacks... but they tend to fall off and leave oil stains on my posters. Still intolerable.
I settled with poster hanger for awhile now.They seem to work fine.. but I found out they also leaves marks where hanger was clamping on the posters and hard to keep still. Whenever I fluffed my blanket or jumped onto my bed, they moved around and, sometimes, fall.
So as I was contemplating possible solution for my dillema, I came up with an idea: Magnetic Poster Holder.
You don't really need anything complicated to 'make' magnetic poster holder.
No push-pin will not work. It needs to be flat head, metal thumbtack.
The picture shown is somewhat round headed.. I just couldn't find flat head one but I presume flat head will work better.
Any magnets strong enough to hold poster will work. I found these magnets at Walmart. Yes, these are probably more expensive than regular disk magnets, but they will be easier to take off.
3. Poster of your liking.
Step 1: Put on thumbtacks
Make sure they are positioned such that they will be located on the corners of your poster
Step 2: Put on magnets
Step 3: Voila you have magnetic poster holder
The magnets I tried held conventional size posters without any problem.
If you have specifically large posters, or if you want to expand this idea to some other wall hangings, I recommend using more than just four magnets.