I will be making a list of really cool Animation packages that you can use to export graphics into Construct.
First and foremost is Pencil. With Pencil, you can create vector or raster based graphics and animate them in a very similar way you would with Flash. Could be useful for lots of appications in character design
Next we have Synfig. This program can create some pretty amazing quality animations. Not only can you create professional level animations, you can also do visual effects and rotoscoping on existing video footage. This program is ideal for cutscenes, making animated character mugshots, selection screens... you name it!
I will add to the list as I remember/find more programs!