Here's the thread on adopting families: Adopt-a-Family for the Holidays?
We submitted a request through the Arlington/Alexandria Coalition for the Homeless, and have had great interactions with the woman assigning names there. We've got all our shopping done now (two little girls are getting bikes for Christmas! And mom and grandma are getting their kitchen stocked with cookware!) so I just have to finish wrapping it all and will drop it off this weekend I hope. Highly recommend it to anyone who wants to participate in something like that.
I also got an email from the DC Foster care group, who said they were 75 santas short as of Monday
Another very worthy place that I've worked with in the past.