Standup comedy. I actually tried it at a few open mic nights when I was much younger, which provided empirical proof that I have no talent for it.
Playing a musical instrument.
When I was a boy, I dreamed of being a rock star. I got my first guitar at fourteen. I have absolutely no rhythm, and bad coordination. You can add me to the chorus(hehe) of people saying sing/dance/play an instrument.
I wish I could play an instrument. But I suck so very, very badly.
I also wish I could draw, but whenever I try, it ends up looking like something Mom should stick to the fridge with a big rainbow magnet.
What frustrates me the most is writing, because I have some of the talent. Just a little. Teachers from kindergarten onward have been telling me I should write. But I just can’t seem to get anything out of me that I can be proud of. I have a blog I enjoy posting to, and I used to journal and do writing exercises, but I can’t get a half decent story out on paper, so I’ve stopped trying. Maybe it’s a confidence issue, but it’s disheartening to try and write something, only to find myself looking for the shredder when I read it later.
Yoga.
Ceramics.
I adore music, but have no talent at any instrument, nor can I sing. I’ve even failed to learn how to make mashups, despite trying several different programs. sigh.
I never made it past 8th grade math and I went to college. I’m a teacher.
But I do agree on the math part: I’d love to be a doctor or a research scientist.
What I really wanted to do - USAF - I couldn’t, but not because I didn’t have the talent. I am deaf in one ear. Immediate disqualification.
How could there possibly be a better answer than this??
Not exactly a talent,but . . . riding roller coasters. I get serious vertigo in those things, to the point of passing out. But I love the concept of roller coasters, am interested in their design, photographing them, etc.
And oh yes . . . dancing.
Anything that requires more coordination than walking. (And even walking, my feet get mixed up sometimes.)
Cake decorating. I can bake a cake so good it’ll make you cry, but decorating it beyond just a smear of frosting? Forget it. Even the smear of frosting doesn’t come out right. My almost 3-year-old niece could probably do a better job. I have no artistic talent whatsoever.
Oceanography.
I am totally, 100% fascinated by the ocean. I would love nothing better than to study it for real, learn about what is down there, discover something new, etc. etc.
Unfortunately, science is not for me. I barely passed high school chemistry and physics, and dropped out of precalculus. I tried and tried and studied and studied and worked like a slave in those classes, but it just wasn’t happening. I think I lack that side of my brain entirely or something. It is one of my secret sadnesses.
On the plus side, I can sing, dance, play instruments, and I’m a whiz with languages.
I have played guitar for over 45 years. I can occasionally make people sit up and take notice, usually by playing somebody else’s arrangement. I have often thought that if I could sing well I would not have bothered learning more than a few chords. I suppose I might like to dance, but that never figures into my fantasies. I am always singing in my fantasies.
Always been an avid reader, have great respect for well-written books, would love to produce a really good novel. (Good by my own definition, that is…something like Ken Kesey’s work, or John Nichols). I’ve done a little bit of journalistic writing and have been complimented on my technical writing skills, but I’m afraid I lack the discipline and organizational ability to undertake anything as complex as a novel.
Also I’d really like to be able to play good slip-note style piano. I can hear the songs and notes in my head but lack the ability to translate that to fingers on the keyboard.
SS
I mentioned playing a musical instrument, but on my trip home this holiday weekend I realized even more than that, I would love to be able to sing well.
Being an idle rich person. I’m sure I’d be able to enjoy the hell out of it and not fritter it away on drugs and bad sexual relationships as so many have. But idleness and wealth are both beyond me, apparently.
I have wished so many times that I could paint that it’s just sad. I can imagine some pretty awesome scenes and designs, but can’t even sign my own name legibly. I would be really happy if I could just paint…for some reason paint rather than draw, hrm…what I see in my head.
I love dancing and singing but fool myself into thinking that I have a modicum of talent and so do those things anyway, just not that well. 
And I’m ok with that! But to paint…<sighs>…ain’t no foolin’ even myself about that one.
This too, though I have myself fooled that all I’d need is a decent garage setup and lots and lots of free time. If I win the big lottery, this is what I will be doing. I grew up with my dad making most of our furniture, and we always had a decent woodshop going, so it’s just inconceivable to me that I can think of this neato bookcase I want and can’t just pop into the garage and knock it out in a few months. <sighs>
Dancing. And for me it’s not so much the talent as the endurance. I’m in terrible shape, and even long-distance walking makes me damn-near collapse. So… Yeah. That.
Like many others : play the guitar, sing, dance.