Question: I am a high school junior and am currently taking AP Calculus BC. I just found out that I received a D for the semester. Will this blow all of my chances of getting into a good college?
If, by "good" college, you mean an Ivy League school or one of the small handful of hyper-competitive equivalents, then your Calc BC grade could hurt your admission chances. While admission officials (plenty of whom may have once screwed up a calculus class themselves) are particularly sympathetic when applicants do poorly in that particular course, at the most selective colleges, you'll be "competing" against students who have gotten A's--or at least B's--in that class, along with 4's and 5's on the exam.
On the other hand, admission folks look at lots of factors when making final choices, and they may find something in your application that they really like and which appeals to them so much that it will outweigh their concern over one poor grade. To help assess the likelihood of this, ask yourself if you have any truly outstanding talents (e.g., music, writing, sports, an atypical hobby) or any additional admission "hooks" (minority status, legacy status, VIP connections, etc.) that might counterbalance a bad grade.
Finally, keep in mind that there is a wide range of colleges that are not only "good" but great. They may not be among that small group that get the most attention on our College Confidential discussion boards and which seem to cause the most admission angst, but they are excellent, competitive colleges where a strong record with one slip in a hard course won't make a lick of difference.
Don't be discouraged. Many admission officials will put more stock in the fact that you tackled a challenging course like AP Calc BC than in the fact that you got that first-semester D, especially if you can pull it up to at least a C in the spring