I use freezer paper as a stabilizer. You can iron the shiny side to the back of the fabric and then just rip it off when done. Works great for machine applique

One of the best things I've been told about and use is, the clear tubing cut thin enough to go around my filled bobbins to hold thread down.

Press and Seal to mark quilting designs.

coffee creamer containers make great water bottles to keep by your ironing board to fill your iron since they have a pouring spout. No spilling and you always have water handy.

I use a make-up brush to clean my machine. I use binder clips to hold my quilt to the table when I pin the top, bottom and batting together. I use salvages to tie up my tomato plants.

Plastic grated cheese bottles with screw on plastic lid. Half of lid can be opened to receive clips, open safety pins, etc.
Large plastic flat ties commonly found as closures for bakery products. Label cords for machine, light, etc.
Re-purpose the detachable trays from older tv tray sets. Stackable trays to hold a variety of block pieces.
Heavy duty commercial type baking sheets with rim to act as pull out tray for items in deep cabinet shelves. Cheap
alternative to pull out trays for lower cabinet usually found in kitchen cupboards.
Colorful empty ceramic flower pot to corral the remotes for tv and digital recorder.
Small rubber gripper square usually used for opening jars provides gripper for pulling needle through fabric.
Leather garden gloves in smaller sizes can be cut to become leather thimbles.
Travel jewelry case with zippered plastic compartments used hold needles, extra light bulb, screwdriver, cleaning brushes, machine attachments, and personal ID for each sewing machine you use.
Letter opener with small amount of razor visible to cut apart units when chain stitching sections.
Tissue paper to copy pattern.
Plastic covers from food items to provide template for circle and/or template material for applique.
Bonnie Hunter's tip for trimming plastic hotel key for drawing sewing line for bonus half square triangle.

I use a mail holder that hangs on the wall over my cutting table to hold small templates and rulers. The hooks underneath that are suppose to be used for keys hold my rotary cutters and scissors

My dollar store also carries them!! (some don't)

I use a wall paper seam roller to "iron" seams until ready to go to ironing board. Ironing board is across the room so I have to get up and move.

I use straight blades as a stitch ripper (when my daughter isn't around), a pair of rubberized gloves to grip the quilt with when free motion quilting, hair clips for binding or thicker seems, j-cloths for stabilizer under my button holes, and a carpenters square for squaring up quilts. Hope that helps!

I also use some of my quilting supplies to help in household projects.