NearBus is an interesting and open-source example of an "Internet-of-Things" platform that works easily with Ethernet-enabled Arduino boards. One example of the use is by monitoring temperature from analogue temperature sensors (or data that can be recorded with an Arduino's analogue input pin) and displaying the data in a graphical form using the spreadsheet web app as part of Google Drive. The required sketch and programming isn't difficult at all, and results with a pretty impressive display that can be viewed anywhere with Internet access:
When putting together your next Internet-enabled Arduino project - save time, space and money with the Freetronics EtherTen. Apart from being fully Arduino Uno-compatible, it has onboard Ethernet, microSD socket, full USB interface (so you don't need a costly FTDI cable just to upload a sketch!) and supports optional Power-over-Ethernet.