1. Atheism: People still have trouble understanding religion and their own position on it. I have no issue with atheism, people's faith is their own matter to solve, but when the absurd critiques of religion start coming out my ears prick up and my blood starts to boil. There is plenty of good discussion to be had here, I like to throw myself in any way I can to make sure it stays within the realm of critical thought.
2. Psychoanalysis: In my opinion this is the biggest joke philosophy and theory ever picked up and advanced. I come accross this much more in my critical theory (rather than 'philosophy') experiences, but when I do my eyes tend to roll. The 'hunt for phalluses' and attributing everything a person does to an unknown psychological force that determines what we do but it fundamentally unknowable has yet to convince me of anything. I spend more time arguing against the results of such analysis than producing my own: as much as it seems antithetical to any sort of 'productivity' I really can't seem to help myself.
3. Renegotiating Terms: Although I am sensitive to the issues of definitions, the absurd lengths some discourses go to define what terms means leads them into positions no longer worth arguing. If you have read Michael Ignatieff on torture you have some idea of how little use this sort of thinking is. Concrete definitions are impossibly: we don't need exact definitions, but rather basic ideas of what we are arguing or else no argument gets done. (I have had this argument about ontology and the nature of Being too many times to count)
4. Evolution: Evolution is well documented and evidenced to make some very specific claims: it is not the end-all explanation for everything. I can follow (although not necessarily agree) with some of the forays into anthropology and psychology, but when evolutionary literary criticism or evolutionary epistemology become buzz terms of discussion I start to get less rational and more enraged. I have thrown things.
5. Pretension: We are all guilty of this to some degree at some time or another: it seems to be the result of constantly thinking and reading ideas that most people never consider. My issue is when it becomes a virtue, something extolled and employed as either an attitude or even a method of argumentation. Maybe I have been stuck with some bad apples in my time, but it frightens me how common this is/is becoming.
I also have a special place in my heart (the black part) for Objectivists, but that will get its own rant at some point.