Google+ Badge Prototype
It was for a social-themed hackathon when I was an intern at Google. Google+ was either near launching or had recently launched, and we thought this widget would help notable people/organizations gain followers and make it easier for regular people like you and me to follow people/organizations we're interested in.
I'm positive this would have happened without us, but it was nice to have created the first implementation.
We even received some nice feedback from the heads honchos for Google+, and tied for 2nd in voting out of 30+ teams.
It helped in the hackathon presentation that we had a handy web page from which people could easily get the code for their own badge, which was very similar to the one linked to above.