Character LCD's are a great way to get your project to talk to you, but the number of pins needed to control them can sometimes be a problem, especially with a more ambitious project. This backpack reduces the number of pins required by using simple i2c and SPI input/output expanders.
Will work with any 'standard' character LCD, from 8x1 to 40x4 sizes as long as they have a 16-pin single-line connection header at the top.
Breakout comes with a 2-pin and a 3-pin terminal block which you can snap together and solder to the backpack for easy wiring
For advanced users, this project can be used for general purpose I/O expansion, the MCP23008 has 8 i/o pins (7 are connected) with optional pull-ups, the SPI 74HC595 has 7 connected outputs
Adafruit have put together a lovely product page which includes a tutorial, Arduino library, wiring diagrams and files.