LED matrix wall is suddenly very hot recently. I also make one for fun.
It can be used as a speech synthesis talking face, message display board, a Internet Graffiti Wall , a Conway's Game of Life. ... etc.
It may be quite interesting to add on to a robot for machine-human interface.
It is easy to construct one. I use one atmega88, with ULN2803 and some transistors as drivers. Use 7 + 8 I/O lines multiplexing technique to drive it. You can visit my blog for more information.
https://www.youtube.com/watch?v=o-0FOZcDRKo