I have quite a lot of big crayon and chalk art that the kids have done in school - I've always wanted to hang it but buying frames, even the cheapest, would be expensive in the end.

What's a non-traditional way to protect and frame things like this? (16x20" and bigger - all on paper)

building a shadow box? my grandpa did this for us it was pretty cool he made a HUGE one (i would guesstimate 4feet by 8 feet?) and made a collage of all his grandkis stuff and that way could put things in there that were 3d and the bottom acted like a shelf its pretty cool:D or maybe doing a couple smaller ones? i dont know good luck:P

For just hanging get some wire and hang it across your wall and then get some clips (or even clothes pins would work) and you can easily clip up artwork and change it out if you want. :)

As far as protecting stuff, I know my mom laminated a lot of my stuff when I was little.

hairspray will help with smudging and protect the drawing itself. you can also buy sleeves at most art supply stores for a dollar or so. those can be sealed with tape or glue. the way i did the girls' stuff was to buy the sleeves then we taped the edges shut and decorated the tape and hung it with string. worked for us and it is still pretty flat so we bought a huge book and they are all in there .

not really framing them, but have you thought of getting some string and clothes pins (the wooden ones) and hangling them like that? Kinda like the way they hang paintings to dry.

I have quite a lot of big crayon and chalk art that the kids have done in school - I've always wanted to hang it but buying frames, even the cheapest, would be expensive in the end.

What's a non-traditional way to protect and frame things like this? (16x20" and bigger - all on paper)

If money is no object..... get the drawings transferred to fabric (white cotton bedsheets are best) and make a quilt. Most of the fabric stores can show you how to transfer paper work to fabric.