While this isn't polling as such, I've found the FiveThirtyEight Facebook map of candidates to be intriguing. When you drop out the other candidates, Trump vs Sanders is still a competition as you'd expect, but Trump vs Clinton... she barely shows up. Her number of Likes is surprisingly low.

http://projects.fivethirtyeight.com/facebook-primary/

I'd usually ignore Facebook likes, and FiveThirtyEight insists it's for fun as well. However, their throwaway comment "If Facebook likes were votes... Donald Trump [would] garner more support than Ted Cruz and Marco Rubio combined" has actually proven to be accurate.