Do you need to write a paper for a field course? Are second/third year paper deadlines quickly approaching and every time you think of an interesting question, the necessary data does not exist or there is no exogenous variation or.. We have all been there. My suggestion: Have a peek through this website which compiles information on plausibly exogenous sources of variation. It seems a bit backward, but you may be able to link a right hand side variable from the website with an outcome that you're particularly excited about. Good luck!
H/T: Treena Goswami