Thanks yannis, these are some great comments. With regard to the social graph one, I've heard advice akin to this from several people: that the person is more

Thanks yannis, these are some great comments. With regard to the social graph one, I've heard advice akin to this from several people: that the person is more important than the topic when it comes to advisors. When you look at the PhD as a license to carry out research, rather than a major work itself, this makes sense. But it is sure hard to force yourself to adopt that attitude when you're in the middle of it. From the student perspective, it is tempting to make the argument, "This professor doesn't fit my personality, but I really want to work on this particular topic." Regarding scalability, what you say makes sense. Indeed, I am a bit jealous of people with a bio- prefix; they are in the same spot computer scientists were in a few decades ago. As far as my personal background, I am a Computer Science guy with a background in the systems community (semantic web, databases, web architecture) who is interested in getting more into machine learning. I'd love any advice on where you think the exciting momentum is in that area. EDIT: Re-worded for clarity.