Dennis Haupt discusses how to efficiently export animated models from Blender to FBX.
Exporting to FBX with included animation out of Blender is a difficult thing, especially if you want to use it for 3D web applications like Verold or the coming soon animation feature on Sketchfab, it is important to reduce the animation keyframes, so the animation runs smoother and also the whole scene loads faster.
After the export, the result often looks not like you have made it in Blender, also the export may take a lot of time or fails. This is why i wrote this tutorial. There are a lot of things you need to consider, like the number of keyframes, inverse kinematics and bone constraints are not supported like in blender and it is better to have only one animation in your FBX file after the export.