“Transfer project data from one application to another quickly and easily with the FBX Converter. This utility lets you convert OBJ, DXF, and 3DS files to and from the FBX format.”
All the old forum and blog links I found to it were broken, but the link above works.
It also seems to support the Collada .dae format. However, conversion of a Spore .dae file to .fbx appears to result in the mesh getting lost and just the bones remaining (at least, this is what loading it into 3DS Max reveals). This is probably why, when a Spore .dae file to .fbx is imported into 3DXchange, there appears to be nothing at all in the 3DXchange viewport?
Could be useful for those tough .3ds files that iClone‘s 3DXchange utility has problems with. Also potentially useful for quickly getting those pesky old .dfx files into a format that 3DXchange can read (at least if you have the iClone v4 Pro version).