The Idea was to observe several temperature changes in my home central heating / solar water heating system and see the startup/shutdowns temperature values of the heating circuits.
I made a weather station connected to the internet. It measures temperature, humidity, UV index, rainfall and it calculates few more important meteorological values. It then sends this data to weathercloud.net, which has nice graphics and UX. It also has a weather web camera. It cost me around 150€. I made this station as my school project.