There's usually little you can do to change the mapping of your keyboard in Windows but SharpKeys allows you to make different keys perform different functions.
One practical application for is is if you're constantly accidentally hitting a specific key all the time - such as the Caps Lock key - you can turn it off or move the Caps Lock function to a different key with SharpKeys. You can in fact map up to 104 different combinations although if you did that many, you'd surely end up confused as to where anything is on your keyboard anymore.
For me, one of the most annoying things is when I hit the "insert" key which results in me typing over text rather than squeezing text in between and SharpKeys fairly painlessly allowed me to deactivate this. It doesn't seem to work however for all keys - whether that's because some keyboards are not compatible with it I'm not sure.
All things considered though, SharpKey is a quick and easy way to remap your keyboard keys to a configuration of your liking.