Attached Link: http://www.renderosity.com/mod/rrfilelock/download.php?fileid=27237&key=5138

Ooh, you're right, it *does* allow multiple objects!  The deformation wouldn't really be a problem with a single mesh since you can just use vertex groups, not envelopes--in fact, either way for something like this you should just use vertex groups since everything is spheres.

SEspider:  Since I've been playing with it a bit, I'm attaching a file.  Take a look and see if it makes sense to you.

What I did is create some spheres like how your spider's joints are set up and an armature with two bones, one for each leg segment.  The spheres are all separate objects.  I selected each sphere and added an Armature modifier to it, then typed the name of the armature in the OB: box.  (In this case it was called "Armature"--creative, eh?) I also deselected the "Envelope" option, but I suggest you try reselecting it on all spheres object to see what happens so you can see why I did that.

Since I deselected the Envelope option I have to create vertex groups for all the objects.  I selected the top one, went to edit mode and selected all vertices.  In the Edit panel in the Links and Materials area there is a "Vertex Groups" label with some buttons underneath.  I clicked the "New" button under that label (not the one over to the right!) and renamed the group from "Group" to "Bone.001", which is the name of the top bone, then hit "Assign" to add the selected vertices to that group.  I did the same for the other two spheres, but the group names for those were "Bone", which is the name of the bottom bone in the armature.

All the spheres are also parented to the armature (as an object, not as an armature) which means moving the armature will move all of them.  This isn't really a necessary step, but it's convenient.

If all your spheres are in a single mesh never fear, armatures will still work.  There will just be a single object to add a modifier to, and all the vertex groups will be the same (top sphere for top bone, other two spheres for bottom bone) but they will all be within the same mesh.