Marijuana!
Since the website came up with the nifty feature that allows users to ask, rate, and discuss questions, marijuana is the top-rated question with almost 2000 positive votes.
In second and third place is appointing secretary of peace and non-violence, and passing the DREAM act, respectively.
UPDATE- I want to make it clear that change.org is not affiliated with the President-elect.
I'm making it clear that, regardless of how you view change.org, the true public opinion about marijuana is becoming increasingly visible thanks to the Internet.
Obama has made clear on his stance of ending raids. This issue needs more national attention. No opinions or stances need to be articulated, just cold, hard facts, like the percentage of Americans that think Cannabis should be legalized. Just let that marinate for a while.
UPDATE II- It turns out that marijuana IS #1 on change.gov as well as change.org