I had to look at the new suggestions -- you folks have great ideas!!
Here some more I noticed when I was sewing today:
-- plastic boxes that are for storing the scrap book paper - they hold my finished blocks, the layer cakes, folded 2.5" strips, etc.
-- Coffee cup used as a holder for thread spools
-- small plastic hair claw clips -- I use these as extra thread guides when I use an external thread holder
-- sticky notes -- a stack marks the seam allowance, the extra sticky ones can attach to pieces, blocks or rows so I can write notes
-- laminator -- I laminate my most used patterns so they don't get munged when I use them over and over
-- I second using blue tape -- it is great for marking the quilt for straight line quilting and helps hold things in place without ruining them (if I can keep DSiL and DH from borrowing it). I keep an assortment of widths in my sewing room.
Keep the ideas coming ladies!!