If you're an Animator, this is something you MUST have in your 'Animation Toolbox'. It's a completely FREE software that is ideal for thumb-nailing and planning out your shots (heck, you could even create an entire animation with it!). It's called Plastic Animation Paper v4.0. Fully customizable interface, very intuitive design, take your animation planning to the next level and endless possibilities and what you can do with it!
Go through the tutorials and learn about all this awesome software can do!!
One thing that they recommend is that you have a Wacom tablet, but you can still use a mouse if you don't have one (I recommend getting one anyway, another "tool" for you arsenal). This is amazing stuff, it does a lot and it could really help save time when you're in the planning stage of animation!! I recommend it, and I'm definitely going to be using it on my next shot!