Tons of neat graveyard interactions. Sundial just makes them more awesome. Almost everything that can be in your graveyard can be useful.

A 5/6 flying on turn 4 without exiling anything is nice if you use Postmortem Lunge and a Sundial of the Infinite.

So is a permanent 4/4 flying after using Geist of Saint Traft.

With all the self-milling, your Sun Titan can be brought in with the Postmortem Lunge and bring out two permanents instead of one. For instance, it could use it's enters-the-battlefield effect to bring in a Sundial of the Infinite, and then attack and bring in a land so that it can stay on the battlefield at the beginning of the next end step.