We stumbled upon on hidden from view burger place in the beverly hills area recently, and it gets my vote as one of the best burgers around. I'd noticed the umbrellas in the alley driving by before, and finally had to drive on thru to see what was going on. What's going on is Finney's in the Alley. They're located off Olypic and Clark (Clark is one block west of Robertson), located, yes, in an alley. Apparently this place has been around for like six years, but I never knew about it working in the area the entire time.
I tried their double schwartzberger, a double patty burger dressed with bacon (oh, sweet thick bacon, hohohohoho - sorry, had to go homer simpson there for a second) relish, cheese, avocado and crispy lettuce. The burger is really juicy, and the rest of the ingredients make for a real decadent burger treat. I also tried their sombrero burger made with guacamole, but the schwartzberger is the call. Add to the burger some of their chili cheese fries, and its pretty good mega-calorie overdose splurg. Prices are a little high however, for a burger place - double sch., chilli fries and soda ran me about $11.