1. What is a non-combat interesting way to use earth magic?
Distracting noises for stealth made by rocks, sand underneath shoes to lessen noise while sneaking. A "pillow" of sand to avoid damage from long falls. A nice spell from d&d stoneform allowed the caster to become stone and travel along it reappearing instantly anywhere along stone he was touching. Imagine this in a castle made of stone.
2. What is a single target interesting way to use earth magic?
Believe it or not within your body is all the ingredients needed to form many crystalline structures. With earth magic I suppose you could "crystallize" someone's bones and create protrusions to cause bleeding or perhaps just one right into the brain cavity. The coroner would have a field day with that one.
3. What is an area of effect interesting way to use earth magic?
Theres nasty stuff under the earth in a lot of places, the only thing keeping it from the surface is layers of rock...that you control. In subduction zones there are geysers and lava. In plains areas there are aquifers storing centuries worth of rainfall, underground streams, in cavernous areas there are poisonous and natural gases toxic and even flammable, there are areas where permafrost ice has been frozen and hardened for centuries, expel that from the ground
4. What is an interesting way to block using earth magic?
Magnetic ironsand look it up cool stuff. Fill all your pockets with it and command to your liking. Also under direct sunlight it heats up enough to cause burns if you touch it.
5. What would be an interesting way to impede someones movement with earth magic?
I have one character with enchanted shoes that disintegrate earth beneath him when he activates them. Anyone trying to chase him soon finds the ground beneath them collapsing into a trench.
6.Can you think of anything else that would fit the Dresdenverse and be really neat in a game for earth magic?
Ironsand filled clothes, fun things could be achieved especially with a copper coil around your arm. (magnetic material + copper coil = electricity.)