You can replicate all sorts of commerical products with an Arduino or compatible board and some external hardware, and an excellent example of this has been demonstrated by Instructables member smching whose queuing system could be built for much less than the cost of a retail unit.
The system is split into two parts each with their own Arduino. One side controls a large Freetronics DMD display to show those waiting for service the upcoming number, and the other Arduino accepts input by counter staff using a numeric keypad and also has a small LCD to show the system status. The two partrs communicate with each other via UART serial using Cat5 cable. Finally a doorbell IC is used to generate a neat chime to alert the person at the top of the queue.
As used in the project mentioned above, check out our Freetronics Dot Matrix Displays. They're simple to use, yet very bright for indoor and outdoor situations. Available in various colours, the 32 x 16 LED matrix can display text and graphics quite easily - and can be daisy-chained together for extended displays. For more information, see our range of Dot Matrix Displays here.