Rulers - haven't yet but I'm a novice quilter
Cutting Mats - when they get groves in them
Rotary cutters - haven't yet
Rotary blades - when the skipping gets bad and sharpening doesn't fix the problem
Pins - when bent
Needles - when broken
Chairs - I only wish I could
Sewing Machines - not yet
Scissors - when they get loose and don't cut cleanly
Seam Rippers - not yet