You might remember the science fiction magazine Strange Horizons' guidelines on cliche ideas that are not interesting to submit as new stories. As a follow up, here's another compendium of overused science fiction cliches.
This list is particularly nice. It gives us some facts on each cliche answering questions like "Did it also appear in Star Trek?", "Is it overtly racist?". It rates cliches on one of five levels of acceptability (e.g. still usable when done right, not so bad the first time around but now...). In addition to plotpoints it also lists classics in bad visual storytelling - one of the more memorable cliches is "Only bad guys have goatees". And yes, that too did happen in Star Trek.

(via Just's linkpool)