For me, it is using animation tools, like Adobe Flash. I really don't see the point in using it as a resource. For me, it is much more time consuming to create an entire animation for my students. I don't really see the benefits I would like for all the work I put into making an online animation. I suppose it really doesn't fit my style of teaching, so I tend to stay away from it. I also feel like that using animation tools depends on the content you are teaching in your classroom. For a pre-engineering class, I feel like this is to abstract and not sequential enough.
Now I know this is not the case for many educators out there. Many teachers have probably created tremendous resources for their students, I just don't even think I've come close to being one of them. When I have tried creating different animations for my projects, it has only been when I have been required to do so for my Masters class. I feel like I am reaching way into left field to come up with an idea that will fit into what I teach. I'm sure that with more practice would be come better results.
Here is a list of free animation sites I have tried to use. They are pretty easy, so check them out!