Use your mouse pad...
...as a trivet.
A mouse pad with a non-plastic coating can be put to use in the kitchen as a heat pad, protecting counter tops from heat damage and scratches.
...to open jars.
Most mouse pads (especially the free ones) have a rubber grip texture on their underside that's perfect for loosening the lids from stubborn jars or bottles.
Cut 'em up and lay 'em down to catch condensation from cold cups.
...to line cabinets.
Rubber cabinet liners are cheap, but old mouse pads are free. Line them up in kitchen cabinets to secure your plates and glasses from slipping.
...as cabinet door stoppers.
Cut mouse pads into nickel-sized circles and glue them to the corners of cabinet doors. They'll protect your cabinets and silence the noise when they slam shut.