I think there are two left - Sherman Oaks and Sunset Blvd. (maybe the one in Brentwood is still there - not sure).
A quick Google shows that there are currently seven Hamburger
Hamlet restaurants, although they are now known as Hamlet, Hamburger having been dropped (and the five second rule applies).
In SoCal, they are the Hamlet Pasadena (on Lake - been there, done that), Hamlet Sherman Oaks, Hamlet West L.A., and Hamlet on Sunset (also been there, done that - Log Cabin held a couple of dinner meetings there, quite a while back).
Then there are also the Eate Coast Hamlets: the Hamlet at the Rio (in Gaithersberg) and the Hamlet Bethesda, both in Maryland, and the Hamlet Crystal City, in Arlington, Virginia.
Alas, poor Yorick, while we knew them well (or medium-rare, my doneness of choice), the rest have gone to dust.