My undergrad major was EE (identical to CS, as far as laypeople are concerned) and I just came out of this application cycle with four acceptances, a waitlist spot, and an interview offer at Stony Brook that I declined.
I don't know what your definition of "top" schools is (the most prestigious place I interviewed, in an "oooh, Ivy League," sense was Dartmouth, where I was waitlisted). I will be attending Tufts next year, which is a great school...but if that doesn't do it for you then I suppose you can skip the rest of this entry.
I did some normal EE extra-curriculars: two internships and a position on my school's solar vehicle team. I also did some pretty extensive volunteer EMT work, some shadowing, and I combined my interests by working on mobile application development with a few local physicians. If anything, I think the EE/CS stuff was helpful on the interview trail; most of my interviewers were very interested in my background. One memorable instance was when I spent a good 20 minutes explaining the minutiae what goes into building a solar-powered vehicle...the guy was absolutely enthralled.
Doing CS extra-curriculars will not hurt you, but what will is thinking that doing those gives you license to skip out on the traditional ECs that help pre-meds understand what a career in medicine is really like.
