Ran across this little tribute vid by Pascal Blanche (who turns out to be art director at Ubisoft montreal). It only has a moving mouth, so not actually animated, but it occurs to me how effective this could be if your trying to make a sci fi short and get the most bang for your buck (though I would find something else to move instead of the mouth). You could easily do it with a few 2D images as well.
earlier post on Lou Romano & Will Finn's similar stuff
hands of the master did it a lot by having extensive matt paintings saving time on modeling tech out (the chair for example)