Uninspired sentience

So the thought crossed my mind after Avatar hit Blu-ray and DVD, that every single idea of extraterrestrial, sentient life is tightly bound by existence as we know it on Earth.

I don't think I have ever read a book, seen a TV show or watched a movie that doesn't have humanoid aliens. If the aliens aren't humanoid, the way they do things is very similar, an example I can think of right now is Jimmy Neutron. The alien race they meet in the movie are sentient slime balls in floating robotic suit things. They have robotic arms and hands, all technology and behavior is all human-like. Take a look at Avatar and all you have are tall, blue people with tails, pretty uninspired and uncreative. Take a look at just about any form of media that involves aliens and you will most likely see this : A head (occasionally two), two arms (maybe a second pair), fingers, feet, eye(s), boobs. For some reason we think that the only intelligent life out there will look like us. It may be the case, but probably not.

Two examples where the above ideas do not apply that I can think of are in the old 90's cartoon Dexter's Laboratory and Star Wars. I recall a certain episode of Dexter's Lab where sentient, parasitic gooey things fall to Earth from a meteor and use his family members as their hosts. Next comes the Hutt race from Star Wars, they're giant balls of fat. I don't know if that's what they are, or else they are extremely obese humanoids.