When teaching math to weaker students I had to rely on my creativity, using brooms or teddybears to explain mathematical concepts. Since text books are static they had difficulties with things as "when x approaches to infinity. Since in a textbook nothing moves I took a toy car to ride on graphs on the blackboard. Anything can help when it comes to teaching and lerning.
GeoGebra is a great showing tool. But learning is an activity by students. GeoGebra has become so powerful that a teacher can be tempted to make beautiful stuff so full of features... that thinking and learning by students is prevented. Starting from my own teaching experience I focus on some topics where GeoGebra can make a difference in both directions.