SmartStrip is a sketch for Arduino meant to allow advanced control of relays through a web interface. SmartStrip currently supports always ON/always OFF and temperature-controlled relays, i.e.: a relay can be configured to turn on when the temperature goes above/below a given threshold (with a given hysteresis margin). The temperature is measured through a DS18B20 sensor connected to any pin of the Arduino.
Sukkino is a collection of libraries for the Arduino platform. I originally wrote them for my own projects but I think many arduinists can take advantage from them. It contains a universael webserver capable of delivering dynamic contents, a method for writing runtime assertions and one for reading/writing arbitrary objects from/to EEPROM.