I have this fusible kind of tape, can't remember the name now. But often if I make a small quilt, the batting is maybe 45" wide and if I made the quilt maybe 60", since I have a roll of queen batting, I often have scraps that are 30" x 45", so I fuse two of those together for donation quilts! I really don't have THAT many scraps, I'm pretty good at using it up, I don't think I save under 10" or maybe bigger.
Then I fold them and label them with a scrap piece of paper and a pin, what size they are, plus I have a paper on a clipboard where I note the sizes as well. This way, when I need batting for a quilt, I may have a piece that's big enough or fuse 2 together and I'll use pieces that are close in size. also if I need scrap batting for mini things, I'll know to look for my smallest scrap by looking at my clipboard :-)

I zig zag larger pieces together for donation quilts. Just butt them tightly and sew. i use smaller strips for lining on bag handles. Other pieces, once trimmed and put with a top and backing strip of same size can be used for quilt as you go projects (especially for quick and easy baby quilts). Roll 2 1/2 inch strips into a jelly roll then wrap and tack to hold with a piece of fabric to make a pin cushion. Great for quilt retreat participant gifts. Last nite I just stuffed a pillow with batting scraps. I am a "batty" kinda gal!

I've used the skinny strips that were left over for bag handles. They add a little cushion to the handle and it helps me not feel bad about hoarding my batting scraps.

I have been making some "Patch Abilities" Patterns as Christmas Gifts and they would take about a 7 inch by 24 inch piece of batting so I do keep smaller pieces too.

Stuff them in a bag to multiply? OK, what I meant to say is I will be watching the answers...LOL...I wonder if I could make a pocket out of some and stuff it with sand to make pincushions?

Mug rugs, potholders, coasters, doll quilts..zig zag pieces together for baby quilts and donation quilts...

I save them all for 2 things... I have this wooden crate that my cat loves to lay in under my work table and when I trim a quilt edge if the batting is not big enough for anything I toss it in there to make the crate more comfy for him. He loves it. I also save any size batting scraps to use to stuff things like trapunto or stuffed dolls or anything like that. My grandma never threw ANYTHING away. She even used her teeny pieces of thread that were left as stuffing for things. :D

I save all batting scraps and always find a use for them. The small pieces are saved in large size zip lock bags and other pieces are folded.
Julianne covered just about everything that I use scraps for and Samantha had a terrific idea for a cat comfy bed.
I save my trimmings and threads and send to the quilt quild ~ they use those in pet beds for the animal shelter.

I save anything around 1 inch wide or more. I have a drawer full and I just pull them out and zigzag them together. I use them in any small projects - bags, mug rugs, placemats, etc. and also in baby quilts and up to twin size. I'd love to try the tape sometime but I've never found any.

I have a tub full... for totes, tote straps, diaper caddies, mug rugs and mug mats, etc!