My single worst subject has always been math. I can do the basics, plus some algebra, but was never able to get beyond that...I tried statistics, geometry (got the basic concepts but little more), and while I was able to pass, I don't think I really got anything from those classes. I took trig once and had to drop the class (my books and notes being stolen, leaving a job, and my favorite uncle suddenly dying played a major role there)...
Science has been little better...I did decently in biology and basic physics, but chemistry almost killed me. However, chemistry's a "family curse", so I don't feel too awful about that.
I've always done fairly well in English...not stellar, but decent. History...well, I've been doing well, and I got enough of an interest in the subject that I'm majoring in it now.