Neatorama reader Linnea wrote:

The One Click Butter Cutter is my Dad's new invention - unlike other butter slices, it cuts just one slice at a time and stores the remaining butter stick, too. You can cut a whole stick of bar in just seconds, and it keeps your hands & the butter clean. It took him about 60 prototypes but now the One Click Butter Cutter is finished, and you will likely be able to find it in many major stores by the end of this year.

Link - Thanks Linnea!