The short answer is that I don't think a good standardized motion file format exists and I don't think there are any good generic wysiwyg robot posing tools. Some level of custom programming is going to be required.
RE: Standard file formats for robot motion
Collada is meant as a standardized 3D data interchange file format, and it has support for storing basic animation and physics type information with a model. Support is not consistent across tools though, especially for the animation/physics data.
Beyond that, it's unlikely you'll find any general use file formats for storing robotic animation. (Although not 100% comparable, check out the wikipedia list of motion/gesture file formats.) Everything I have seen is specific to the platform and/or proprietary. Consider that the game and CAD industries are orders of magnitude larger and more specific than robotics. They have similar requirements, yet there is no defacto file format.
If you are interested in a more programmatic view of the data by these proprietary systems though, then looking at the specialized tools used by these industries might give you some additional options and ideas. Examples:
The creation, storage, and execution of character animation (often humanoid), in particular, is well represented and very advanced in the game development industry. For a price. I believe most of the larger studios have an entire team dedicated to doing nothing more than converting data from one system to another and feeding it through a production pipeline.
One recurring problem with using game development tools (or creative type 3D tools in general) for robotics is that in games/movies, is that it's usually okay if the animation doesn't model reality exactly. That can cause issues when applied to real world robots.
RE: Posing Tools
Robotic simulators (like Coppelia's V-REP or even MS Robotics Studio) might be of use if they provided an API/export of some sort and were able to simulate humanoid type robots. I don't know of any that support a full humanoid model though. Most are just for modelling arms and wheeled robots. Still, perhaps you could model your humanoid movements as an collection of independent arm subsystems? i.e. The left leg is one robotic arm. If so, then a few more wsyiwyg tools would be open to you.
Flowstone is another visual tool that could be used for posing, but probably not the wysiwyg that you had in mind.
If you don't need WYSIWYG and are open to some programming, you might want to check out PyPose and Nuke.
Similarly, but requiring more advanced programming, various physics engines might be of interest for taking in all the inputs (3D models and associated parameters) and then providing movement results by applying forces and inverse kinematics. Examples include ODE and Bullet physics. A similar programmatic slanted option would be to use ROS. I've seen a few projects and notes regarding potential ROS support for humanoid type motions.
All that said... although difficult to learn, I still think Blender3D has potential to be one of the better all around options for advanced hobbiest type robotics posing and motion work, particularly due to it's tight integration with the Python programming language. Someone already pointed out the Blender Robotics wiki in the comments. You should also review Grantlo321's YouTube video using blender to control servos playing a piano, as well as the blog post by Justin Daily where he describes using Blender/Python for servo control. I agree that Blender3D is hard to learn, but that is likely going to be true with almost any 3D wysiwyg type software unless it's focus is very narrow.