Chain Rig

First, Add....

1 path ( chain_path )
1 Line segment mesh ( chain_guide )
1 armature ( chain_deform ) * Note that we'll duplicate this later on, and make it for animating.

Subdividechain_guide w/ same amount of points as chain_path. Ensure both chain_path, chain_guide are the same dimensions, and length.
Add hooks to every point of chain_path, name them front to back, starting w/ path_hook.001, pathhook.002, etc.
Create VGs for each vertex in chain_guide, name them corresponding to the hooks. E.g. path_hook.001, path_hook.002.
Create bones for every hook in chain_deform. Use 3d cursor snap to make it precise. Name them accordingly, starting with path_aim.001, path_aim.002, etc. Make sure they have an entirely flat hiearchy, i.e. nothing is parented to anything.

Add thecurve deform modifier to chain_guide, using chain_path as its deforming curve.
TrackTo constrain each bone of chain_deform to the vertex in chain_guide that's in the same spot as its tip.
CopyLoc constrain each bone ofchain_deform to its corresponding hook. The hook that's in the same spot as the root of each bone.

Duplicate chain_deform and call it chain_animate. Maybe give them a different display, so the two armatures are easy to distinguish.
ChildOf constrain each bone of chain_deform to its corresponding chain_animate bone.
Add a 'Feed' bone to chain_animate. CopyLoc constrain chain_guide to the Feed Bone, and lock off the axis that aren't aligned with the curve. Lock off the same axis of the Feed Bone.