I’ve long been interested in how those scrolling LED signs work. There are snippets here and there throughout the internet but not everything that one really needs to achieve a project like this. I have actually seen this project all the way through, from breadboarding, to etching my own controller boards and assembling the prototype into a nice package. I have learned quite a bit, especially about using the timer interrupts of the AVR microcontrollers, using shift registers, and especially about selecting the right hardware for the job.
Take a look at the in-depth tutorial I have posted at instructables: