Not to perpetually beat the drum of Watertown, but there is a really excellent thin crust place right in Coolidge square which is the little neighborhood on Mt. Auburn that is also home to Arax and Sevan.
I am not even a thin crust fan; in fact, I prefer Sicillian, but Stella's has excellent, very thin crust that is done perfectly.
They do all the standard toppings.
Only sell slices at lunch and the slices are thicker then when you order a pie.
Really a neighborhood place, but top notch pizza for anyone who is a real thin crust fan.