So the first tool I want to let everyone know about is the Compounding Interest Calculator by NerdWallet.
Here is a sample screenshot:
The reason this tool is so powerful is because it allows you quickly figure out how much compounding interest you make based on the money you are investing or saving. You can use this calculator to enter the values based on your personal financial situation and then decide how you want to modify your investing or savings behaviors. I personally spend a lot of time playing with this calculator by different values to view various financial outcomes. Its helped me quite a bit and I hope it does the same for you!
You can find the tool here.