Extocracy: Government by extraterrestrials. All governments have been extocracies since August, 1959.
varlosZ must have forgotten to inculde this in his list:
EXTOCRACY: You have two cows. The extraterrestrials mutilate one of them. You get an anal probe.
I hereby propose: wevetocracy: Government by me.
If I am unavailable… well, don’t do anything I wouldn’t do 
Well, a possible new one would be a government run by big corporations. This is the topic of the cyberpunk novels, etc…but not unreasonable given the enormous amount of power they already have in US govt (particularly with REpulbicans).
I think what we’re discussing is mainly an issue of language. There haven’t been any newly-named forms of government because nobody has seen fit to change the names of the existing ones. Innovations in government forms, like the Athenian democracy or the American Constitutional Convention should probably be viewed as anomalies. Governments change and evolve all the time, but our culture doesn’t demand a new name for things unless there’s some extraordinary, sudden change, or a need to make a perceived break with the past.
England is a good example. It was a monarchy that has evolved gradually into something more closely resembling a democracy (in the American sense) but because it has done it gradually, no one has felt the need to reclassify it or create a new name. And they won’t, unless a very strong reason develops for the parliament to want to disassociate itself from the royal family.
Imho, I would consider communism, socialism and capitalism to be economic systems rather than governments.