The butterfly spline is a prominent way to shore up a damaged piece of wood in a way that shows off the joint instead of hiding it. Take a look. I've only used this skill a few times in the past few years, with varying results. But overall the installed spline was a beautiful repair to a split piece of wood. One of the things I love about this type of inlay is that it allows for basic practice with a solid durable piece that can take some abuse and still come out great. Take a look at this tutorial that walks nicely through the steps to make this simple joint.
After taking a look at the steps I'm willing to bet you'll be looking around for a cracked piece of wood as soon as you're done reading all about it. Take your time, and enjoy the experience of building a new skill that can really shine on your next project.