I think personal health monitoring is probably the most important thing on that list. The thing that excited me the most when smartphones started becoming popular was the prospect that they could coordinate data collection from a number of sensors always collecting data - basic ones like Nike+, but perhaps also sensors measuring sleep, taking periodic bloodwork, etc. At the same time, perhaps you could automatically…
Science is based on probability theory. Until we discover the "grand theory of everything", out other theories will be only approximate, and out experimental results not 100% predictable. Therefore, scientists consider a prediction as correct if the chance of predicting something at random is less than some probability, usually 10%, 5% or 1%.
However, for this to work, each study must be based on new data. If you use the same data to check e.g. 10 predictions, each of which has 10% chance of happening even if incorrect, you will in average confirm 1 of your predictions, even if all are incorrect!