7-Segment LED displays may be mature, but never obsolete. Sometimes used to give a vintage look, sometimes because they are simpler to interface, sometimes because they are tougher than LCDs... Justblair wanted to make a serial-interfaced module with 8 pre-wired 7-segment displays for his projects that he makes with the Arduino. Maxim has this MAX7221 chip that was perfect for his requirements. The chip communicates with Serial SPI, which is repulsively simple to implement.
Check out the worklog he made for this project.