That is an excellent one. Other wave analogies I've heard is
   self-reinforcing waves as structural to memory/idea formation
   itself - standing waves I think they're called. Lots of neat
   stuff you can do with waves and analogies. There's also the
   machine analogy, these days analogizing ideas to computations
   (and computers, no matter how complicated, are easily analogized
   to switches and levers or a telephone switchboard or the
   Internet easily). Another analogy that's commonly used and
   powerful is with plants, with roots, soil, etc.