Try W3VPR or K3CUJ. VPR is a linked system with repeaters in north and south Anne Arundel County. CUJ is a repeater near Howard High School in Columbia, MD. There are usually people listening and there are generally daily nets during the morning and evening drive times. As far as the repeaters IN the city, I don't think they are used that often. I know one of them has an evening traffic net, but it seems like they are more into just passing along any messages than ragchewing. There is also another repeater that is sometimes monitored, W3PGA, in Middle River.