Hi everyone,
I am currently in the process of making a web-interface controlled scoreboard with freetronics DMD displays. They are very bright, and they have an official library on GitHub which is really comprehensive and user friendly (especially GitHub - freetronics/DMD2: Beta release of a new Dot Matrix Display Arduino library). I am driving 9 boards at once with only an Arduino Uno (3x3 daisy chaining), and the update data is sent with Serial port from a Raspberry Pi / PC.
A few things I would like to point out from the difficulty I encountered in this project is that Serial I/O while driving DMDs should have a relatively low baud rate due to some unknown reason, probably SRAM usage. My program started with the highest baud rate (115200) with the CmdMessenger library and it didn't receive data at all -- after lowering it to 2400 it works.
Second is that on the hardware side, if you want to do vertical chaining the cable that shipped with the DMD is only about 30cm long, so it won't be long enough -- I recommend going to shops like Jaycar to get 16 way IDC cables and connectors and crimp them yourself(vice clamp works really well!)
I will release my project up on Github and post the link after it is done.. If you have any questions or thoughts regarding using DMD boards please post them here, as I might be able to help:)
They are super cool, check them out (and only $30 each!):