Even if you have one or more diplomas tucked away in the attic, don't miss out on all of the excitement of back-to-school. You're never too old to learn something new. Whatever you've always wanted to learn more about (from drawing apples in a still life painting to putting in a zipper) chances are there is a class available and open to all. Inquire at senior centers and community and technical colleges. You are sure to find a wide variety of non-degree courses on tap. From the philosophical to the practical, these courses will provide an opportunity to gain fresh insights, pick up a skill, or brush up on an old one. Planning a trip abroad? Language courses specifically tailored to travelers' needs are a popular option. Or travel and learn by participating in one of the 8,000 courses available through the non-profit Elderhostel program. Visit its Web site at www.elderhostel.org to find out more.