[pjungwir]

- Politics: Predict which candidates/bill will do well. Or predict which bills you might care about. Identify the strongest features. Publish a writeup with nice maps/charts. Inputs: FEC donor data, vote history.

- Sports: Predict game outcomes, player performance. Make money playing fantasy sports?

- Real estate: Build a better tool for house assessments that identifies "comps" and predicts what the house should cost.

- Astronomy: Something about exoplanets?

- Amazon prices: Find opportunities to buy/sell.

- Stock prices: Inputs are news/Twitter, outputs are predictions of closing price.

I'd start with your hobbies and go from there!