This class used to be called Essay Writing - I believe it's now called The Art of the Essay.
The singular best course I've taken the Columbia system. Shelly will not only teach you how to write better papers, but also how to consider your emotions and daily life occurrences in creative ways. I learned to write in ways I have never even considered before: one such technique, which she informally calls "juggling balls," works by carrying a metaphor from one anecdote to another and using the two to develop a common theme. She'll teach you these writing methods through example though - no lecturing on a blackboard. All techniques and stylistic methods that Shelly teaches she'll teach by pointing out specific usages in an the example reading, and then working with you to use them in your own writing.
Take a look at Jo Ann Beard's "The Fourth State of Matter" via Google. She teaches you to write like that.
The course is seminar style, with approximately 15 students. You'll get to know your classmates (and Shelly) incredibly well due to the personal nature of the essays, and you'll become really close friends who help each other improve. Class meets once a week, which is a pity, because I wouldn't have minded if it met more often.
Disclaimer: I'm a biochemistry major, and have no extensive background in writing. I still loved this class more than anything else - it's simply that amazing. Take this class. You won't regret it.