I have freezer paper in my sewing room to use for paper piecing--the method that you don't sew through the paper.
I have the tissue paper used for wrapping gifts in gift bags to trace quilting designs on which I then tape to a quilt on the frame and quilt through it. Much cheaper than vellum or the special paper sold to longarmers.
I claimed a 36" square kitchen island after our remodel to use as my cutting table. Rotary cutters, blades & templates are stored in the drawers & scraps, UFO's, & orphan blocks are stored in the bottom.
I use blue painters tape to tape the tissue paper onto quilts & it holds the leaders on the poles of my frame.
Hairspray to keep chalked quilting designs from rubbing off.
Silicone spray to keep the rails on the frame slick and the bed of the sewing machine.
I used to have a roll of Press 'n' Seal in my room for quilting but I didn't like the little bits of plastic left in. Others still swear by it.
I steal hubby's big carpenter's square when I need to square up a large quilt before binding it. And he occasionally has to come into my sewing room to find his level if I've been adjusting my frame.
I have a small, rolling tv/microwave cart that fits under the frame. Usually my embroidery machine, stabilizers & threads live on it but I take the machine off to put my laptop that controls the PC Quilter on when I'm using it to quilt.
I have one of the rolling plastic storage drawer things advertised for scrap bookers that I keep all my thread & needles in. It just fits under the sewing cabinet when it's opened up so I can just reach down, open a drawer & pull out needles, thread, or bobbins when I need them.
I use a coffee mug to keep my little Clover iron in & I use it to put troublesome thread in when it lashes too much on the normal thread holder spindle on the machine.
I like to use used fabric softener sheets to sew my applique shapes onto so I can turn the seam allowance under before stitching them down to the background fabric. It really helps to keep those little pokies under the piece. It doesn't add bulk so I don't have to cut it out from the back side like those who use paper do.
I'm sure there are lots of other re-purposed & purloined items in there, also--LOL!