In Kabbalah, klippoth are sephiroth which are considered to be empty and/or broken. Considered to be a bad thing as they tend to drain your energy or at the very least block your flow of power.
Following discofever's "trickle-down" analogy in sephiroth, think of klippoth as being similar to clogged or leaky pipes, producing a really nasty mess.
It's rather like this node which may
have served a purpose by filling in
some info missing from the sephiroth
node, but is slowly draining my XP.