The EtherCard library on GitHub can be used to send and receive Ethernet packets via an Ether Card board, or any other expansion board with an ENC28J60 chip. It’s based on an initial implementation by Guido Socher and Pascal Stang, but has since evolved considerably.
The RTC library on GitHub can be used to connect to a variety of I2C-based Real Time Clock chips. It includes to ability to set the RTC from the last-compiled date, which makes it easy to get the clock running at the (aproximately) correct time.
GLCDlib includes a large set of monospaced and proportional fonts, as well as some optimisations to improve refresh rates when only parts of the display change.
This code was adapted from the arduino-tiny project, but has not kept up with changes in the way the Arduino IDE now handles hardware platform differences.