I bought big cardboard sheets of different colored paper, I would put an art piece on a colored sheet (whatever I thought complimented the art piece. and photographed it with a digital camera. This way each piece was "framed" and more interesting.
Then I uploaded the photos to a web program (called mypublisher.com and they always have free or discount offers). I made flip books with the art and usually I get an offer at the end to buy a second or third copy of the same art book for little to nothing so I do that and give a copy to grandparents and save one for my kids when they are older.
I found this was a great way for me to both keep most of the memorable pieces yet not have to actually "keep" them. That being said, there were a very small few that I did actually keep but most went into the flip book.
Good luck.
D.