Parchment paper is great for baking. Its heat-resistant properties also make it an ideal pressing aid. When pressing seams open, place parchment paper between the seam allowances and the garment to prevent imprint lines. Parchment paper can also be used to protect areas of the garment you don't want to expose to heat while pressing the rest of the garment.
Freezer paper is used by quilters as an aid to cutting and pressing small appliqués. Be sure the shiny side of the freezer paper faces the fabric and the paper side faces the iron, or you will have melted plastic on your iron. For illustrated instructions, see: freezer paper appliqué .
Table knives or cans of tuna make great pattern weights. There is no need to spend more than $10 at the fabric store for a set of pattern weights. Just lay out your pattern, placing just enough knives or cans on each piece to hold the pattern in place for cutting.
An empty coffee or tea tin can be used as a cone thread holder by placing the tin on the floor behind your sewing machine, putting the cone of thread inside, then pulling the thread end up and threading the machine as for a regular spool of thread. I improvised this myself after my son used my pricey cone thread holder as part of a science project!