Voxels have been around years but have seen relatively little use in computer games. For years, the majority of 3D computer games have been made using polygons, because of there inherently low memory usage and fast rendering algorithms. This pushed graphics hardware to be designed specifically for the purpose of drawing millions of triangles as quickly as possible, which meant that voxels never reached their full potential.
The most popular and most recent game which uses voxels is "Minecraft", which has a landscape of oversized voxels. However, it's voxels are so large, that I would question whether it can truly be called a voxel game.
Going back a few years, the popular series "Worms" entered the 3rd dimension in "Worms 3D" using a mixed polygon and voxel engine to mimic the landscape deformation seen in it's 2D games. It was this game which made me curious about 3D destructible land.
At the start of the millennium, one of my favourite games, "Command & Conquer: Red Alert 2" was released, which uses voxels to render it's vehicles. I first encountered voxels when I looked into modding this game.
In my opinion, these three are the best use of voxels in computer games which exist today. Of course, that isn't saying much, when you consider that two of them don't even do it properly.