Approached by the Memorial Church Cambridge, to create a low-cost active display, I built them a simple standalone unit powered by a Raspberry Pi, with an accompanying browser-based dynamic display page.
Rather than using a rotation of static images, a browser-based display means the client has control over a dynamic display, and can update it remotely and instantly. The display can easily incorporate real-time information (the first iteration of the display software included a clock) from many sources. Mini-computers such as the Raspberry Pi make creating a custom display much cheaper to build and install. The Pi in this unit sits snugly behind the television in a custom case!