Check out the University of Chicago’s College Admissions Tumblr. It’s a great mix of official and zany. And I’m no expert or anything, but I think they may have won the unofficial “Call Me Maybe” meme contest.
It is possible — and desirable — for traditional institutions like universities and libraries to take a lighter approach to interacting with the public. It humanizes the organization, and shows that while we take what we do very seriously, we have a sense of humor about it.