There is a great opportunity tomorrow and Sunday to gain free admittance to some of the lesser-known DC museums that normally charge a fee for entry. It's the Dupont-Kalorama Museum Walk. Participating venues this year include the Christian Heurich House, The Anderson House, the Phillips Collection, and others. There is a free shuttle that makes regular stops at all of the venues throughout the weekend, but I find that most of them are within reasonable walking distance of one another. If you haven't visited any of these museums or it's been awhile, I think it would be well worth your time (and again, free admission to all of the participating museums tomorrow and Sunday).