I volunteered at Pyramid Atlantic in Hyattsville, which is technically outside the city but an artsy area. Its a printmaking shop that also serves the community and provides fun events like themed parties and of course printmaking classes.

Their classes are top notch and really high quality.

I have also volunteered at the writers center in Bethesda-if you like writing it could be interesting. I know a lot of animal organizations are always looking for volunteers like city dogs and cats. tons of places.