The first year my husband and I were dating we were constantly giving each other love notes and cards. Though that has slowed down quite a bit I didn't want to lose these precious memories. I scrapbook, but I didn't want these displayed in a scrapbook because they were just for me and him. So I took a pretty 12 x 12 piece of scrapbook paper and folded and glued it into an envelope. I then added all my paper keepsakes to it and put it in my wedding scrapbook album. This could be done with a child's artwork, notes to mommy etc. Great way to store them.
You can scan them and store them electronically. Send them all to a special gmail account where they will be safe. We did this with our memorable IMs, actually!