I was chatting with a Shaman friend recently who informed me that although it used to be the case that Sentry Totem arrested your fall and allowed you to cast spells in mid-air, they fixed that a few patches ago, and now the spell is utterly useless. Off the top of my head, other spells that leap to join the ranks of the relatively worthless are Mind Soothe, Detect Demons, and Rupture, but I must admit that none of them seems as bad as Sentry Totem.
I don't have a real problem with Blizz keeping spells like this in the game, even though nobody uses them, because after all, you can just not buy them (I haven't bought any ranks of Feedback), and if you do, they're mostly good for a laugh now and again anyway. But still, one wonders if they think Mind Soothe would be overpowered if it couldn't be resisted, or what.
So: what's the most useless spell and/or ability you can think of? Feel free to play defense too -- are there many good uses for spells like Sentry Totem or Rupture that I'm just not clever enough to have thought of?