Google calls their seasonal holiday logos "doodles", and in the absence of a better term, I'll refer to them as doodles, too.
This may seem like fluff, but it occurred to me that our call-centre employees—users of the software on which I currently work—might benefit from doodles that reflect our employers' current marketing campaign. Especially when the marketing campaigns are about a customer need or a pain point, this could remind the call-centre reps steer the conversation and reinforce the message.
This is the Contract Monster (watch the TV commercial on YouTube). This thing is a life-sized suit, currently on display in the lobby of the building where I work. It featured in a series of ads, earlier this year. It—and any of the company's other ad campaigns—could be the basis for an interesting doodle.
We haven't yet had time to implement doodles of any sort, in the UI. I wish we could, though, because during our product research (an early usability study), a small number of respondents said they have to look at the interface all day, and they would like it to be more colourful, less boring. This was clearly a response to the dreariness of the alpha version we were testing, so before any skinning.