I’ve seen a lot of mine already posted here (lots of “yeah, me too!” nods as I read along), so I’ll repeat a few and add a few more:
Coffee - I want to like coffee. It looks good (especially in foo-foo coffee drinks) and every time the spouse orders one I ask if I can try it, to which he replies, “It tastes like coffee, you know…” and I nod sadly and skip it.
Beer, wine, and 99% of liquor: I like Drambuie, Amaretto, and occasional scotch (and by “like” I mean “can tolerate drinking a bit of it”). The rest–feh. Tastes like…yuck. I guess I’ll never be an alcoholic, at least. 
Most vegetables and fruits: although I do like some of the “unpopular” veggies like cauliflower and broccoli. Nothing raw, though. Cook it up or get it away from me. And, to follow logically:
Salads: How I managed to lose over 100 pounds without ever touching a salad, I’m not sure. But I can’t stand the things. The lettuce is yucky, the dressing is yucky…about the only part I like is the croutons.
Seinfeld: Can’t stand it. Tried to watch it once, and that was enough.
Baseball: The most boring sport on Earth. Most of it consists of a bunch of guys standing around scratching themselves and spitting, punctuated by occasional brief spurts of activity. Okay, golf might be more boring, but it’s a toss-up.
Jazz: Yeah, me too. I don’t get it, I don’t enjoy it, and listening to it makes me vaguely anxious.
Babies and toddlers: I’m childfree and don’t find them cute, their antics amusing, or anything about them appealing. On the other hand, I become a puddle of goo in the presence of kittens, and think most puppies are cute. Needless to say, I don’t go around admitting this in too many places–I just avoid places where small children are likely to be foisted at me.
“The Princess Bride”–I didn’t see this one on anybody else’s list. I’m an RPG geek, and it seems like one of the qualifications for an RPG Geek Card is to like this movie and be able to quote it incessantly. I don’t and I can’t, and I just don’t see what everybody sees in it. I’ve tried to watch it twice and both times I fell asleep.
Monty Python: It’s not that I actively dislike Monty Python stuff (which is good because I’d really lose my geek card if anybody found that out). Some of it’s funny. Some of it’s hilarious. But a lot of it isn’t, at least to me. And again, I can’t summon up a MP quote for every occasion like many of my friends can.
Roller coasters: I used to love them as a kid. These days all they do is give me a headache and make me vaguely worried that something mechanical is going to have a catastrophic failure while I’m riding. I still like Space Mountain at Disneyland, though.
