Here is another standing desk mat that lets you work and stand in a more comfortable fashoin. The TerraMat Standing Desk Mat relieves the burden and pressure from standing, so you can stand longer without aching feet and legs. It has 3D features that offer over 11 different possible stances.
This comes with massage mounds to treat the soles of your feet. It also lets you stretch your outer calf and hip flexors. Sets you back under $94.