I think Julia is probably the most enthusiastic developer I've ever encountered. Which is quite a statement considering a lot of the subject matter is (IMHO) pretty mundane.
Did she do a talk at strange loop about system calls? Her Google interview story was hysterical if it was her
Edit not on mobile now. I was randomly looking through strange loop videos and watched one of her. Her enthusiasm and attitude are infectious. Its so fun to watch her be so excited that she gets tripped up trying to decide which awesome thing to tell you. I saw no picture of her on the website i viewied but surmised from the other comments here. Great video and seemingly an amazing person.
The google interview story is superb to hear if anyone hasn't watched yet.
She's also a great writer! Somebody should talk her into writing a book! It's not just that she is enthusiastic, she is able to inspire that same enthusiasm in her readers, too (well, at least in me).