Feature Photo: monique / Photo above: NREL Solar DecathlonMany national non-profits make their homes in Washington, D.C. and are looking for volunteers. For those of us who have a spare moment to volunteer while visiting the nation’s capital ( it’s a great place to experience, but you’ll have some free time once all those monuments start to look the same), volunteering with local organizations can make all the difference in the lives of your fellow American.