Raspberry is a great small Linux machine which is ideal for connecting things to internet. Bunch of O/I pins allow connecting peripherals and sensors that can be accessed via web interface. Ferran Fabregas has been building a weather station with Raspberry Pi which sends data using Twitter application.
Currently his set up reads temperature and humidity data from DHT11 sensor and light intensity with LDR photocell. Raspberry Pi runs a python script which takes care of reading data from sensors. He also runs a local webserver where data can be loaded in nice graphical format which is updated in real time.