Eki stamp and postcard trading

Are there any online groups for people living in Japan who want to trade "eki stamps" / stamps from tourist spots, or postcards?

I've been living in Kanazawa for three years and traveled to many places in Japan, but sadly I didn't think to get the stamps or postcards when I was there. Now I'm making a scrapbook and regretting it.

If you know of any website for people who collect and trade these things, please let me know!

Postcrossing

I found a few blogs (in Japanese) where people display their eki-stamp collections. Some of them display in good quality resolution, so you can, in theory, copy the images and print them. That won't be the same as the real stamps, but may be good enough for your purpose. Personally speaking, those stamps don't mean much unless you stamped it yourself. Also, from my personal experience, a lot of stamps (more than 50%) are in such poor shape (rubber worn out and/or ink pad was dry), that even if you had started collection from day-1, you would not have a complete display-worthy collection.