I will keep you informed. I go to like three events per month.
there is:
BMW
http://www.nccbmwcca.org/
Porsche
http://www.pcapotomac.org/ and
http://www.pcachs.org/
Capital Driving Club
http://www.capitaldrivingclub.com/
SCCA
http://www.wdcr-scca.org/
These are the organizations with frequent events. There are others as well.