There are sooooooo many smaller memorials in DC, I feel like I should highlight a few just for fun. Previously covered were the Marconi statue, the Victims of Communism Memorial and the McClellen statue.
Right off of the 42 bus, near Dupont Circle is a small park dedicated to the late Sonny Bono. The former entertainer was elected to Congress out of California in 1994 only die a tragic, accidental death in 1998.
Sonny Bono Memorial Park is not much more than a plaque attached to a traffic island on New Hampshire Ave NW at 20th St. It is walking distance from a 42 bus stop and relatively unnoticed by most tourists and residents, at least while I observed. There is one Japanese maple tree, planted to honor his service to California (from a nursery in his district) and a few small benches. The park is supposedly kept up over time by a close friend to Mr. Bono; the same friend who lobbied for and financed the park's creation.