How to apply shape keys? I used shape keys to create a middle shape between other two. Can I now remove shape keys and 'apply' them as a modifier to the resulting mesh?
Try creating a new shapekey by pressing the arrow under the add/remove buttons and selecting new shape from mix:



This will create a new shapekey from the current mix. You can then delete all the shapekeys, making sure you delete the new one last.

This gives you a shapekey-free mesh with the shape from the original shapekey mix.