It is well-established that summer is the best season. It is also well-established that 68% of Earth's landmass is in the Northern Hemisphere. However, only 25% of the year sees the Earth tilted at an angle to give the Northern Hemisphere summer. If we kept the Northern Hemisphere tilted towards the sun all year, we would be able to grow more crops, create more solar energy, and save on heating costs.
The technology for this does not yet exist. I believe the best way to do this would be to fix an asteroid perpendicular to the plane of our orbit, tan(67 degrees) AU north of the sun. Fix a stake in the north pole, and tie a string from the stake to the asteroid. This will hold the planet's axis 23 degrees tilted towards the sun throughout our orbit.