Kathleen Sebelius
This one is kind of "out there", though certainly not as far-fetched as Kamala Harris. Sebelius was rumored to have been interested in a presidential run in the 2000s, but didn't run in 2008, possibly because of Hillary Clinton's candidacy. She'll be 68 years old on election day 2016, just one year younger than HRC, which is kind of old for a first time presidential candidate.
I've always had the feeling that President Obama had big plans for Sebelius. She would've made a better runningmate than Biden, but perhaps he thought she'd have a better profile heading HHS during monumental healthcare reform. That is, of course, assuming he didn't anticipate so much backlash on Obamacare.
