I love the Tado temperature/humidity graphs. However, the ability to only see the data on a day by day basis is restricting. The ability to download your data for use in a spreadsheet (in the same way that Fitbit does with its far more complicated data set) would be extremely useful.
For example, it would be possible to calculate the U value of your room given the outside temperature and inside temperature
You could optimise energy usage and comfort by understanding exactly how long each room takes to heat up/cool.
There are likely to be plenty of more uses that users come up with given access to their own data