postcard wall

Recently, I found a fun purchase at Anthropologie.  A box of 100 Penguin book cover postcards.  The plan I immediately started forming in my head was to create some kind of wall covering with the fun, colorful cards.  I have a few places in my apartment I'd like to put a few.  My only issue is trying to decide how to hang them.  Options: cheap frames from Ikea, hang from nails/pins with twine, or hang directly with pins.

[The purchase that started it all.]

 [Temporary tape to help visualize the process and the blank slate where I plan on putting them.]

 [Temporarily finished product.]

So, I like the overall look and know I want to put them here, but I'm still trying to figure out a more permanent solution. At least I don't have to look at a blank wall until I make up my mind.