I was wondering what sort of hobbies are common among applicants, and which ones are often included in entrance essays (For example: sports, foreign language, etc.).
No two applicants are the same...put your hobbies into the essays. As long as you're passionate about them, the admissions committee wants to hear about them. Don't take up hobbies or ECs because you think that's what the admissions people or your congressmen want to hear.