There's a local a capella group named After the Storm. They consist of 2-4 black men, who I'd guess are in their mid 50's to early 60's. The only reason I know their name is that Washington Post columnist John Kelley wrote a piece about them. They perform primarily at metro stations. I used to see them a lot at the Crystal City station and every now and then at Vienna. But it's a long time.
Tonight I had an errand to run downtown after work and was stressed out because both transportation and the errand itself took about twice as long as they should have. But I was changing trains at Metro Center on my way home - and two of the guys from After the Storm were singing on the platform. It cheered me up instantly. I gave them a few bucks and told them how glad I was to see them. I got a thanks and a hug in return.
Keep your ears open in the Metro this holiday season for the best renditions ever of Jingle Bells and Rudolph the Red Nosed Reindeer.