Here's my solar controller, which involves master/slave Arduinos, an LCD, a real time clock, a range finder, and EEPROMs, so there should be plenty of example code in here for those who are hungry for that sort of thing. Most recently I created an interactive menu system using an LCD and an IR mutifunction remote (the code is all in the slave arduino).
Watch me narrate the menu system here:
more details here:
http://asecular.com/projects/homebrewsolar.php