I blogged on that experience and then contributed to a JISC webinar on the same topic.
Our approach is open-ended: it should be able to embrace new solutions that become available to the library. The idea is to re-use the content the library generates in a variety of ways. Here is another example of that.
Last year the library got its hands on old(ish) plasma screen and PC; the screen is now mounted on the wall next to two MFDs (multi-functional devices: printer, scanner and photocopier in one piece). These MFDs are the most used in the whole college, mostly by learners: small queues are a normal picture there, so the location for the plasma screen is perfect.
The screen is used for publicising library services and resources, as well as tips and advice. Recently, other college services have started approaching the library for publicity opportunities.
We use PowerPoint to create simple slides which then are displayed as PowerPoint show on the loop. Most of the content comes from what's already been published on the library blog, - the main repository of the content generated by the library. Roughly once a week the slides are refreshed, new content is added, something removed.
Here is an example of the file used on the screen (PDF).