A place I’ve found to be good for idea hunting is the website for the city I live in which has all sorts of interesting and useful information that is often organized horribly or hard to find.
One example was that they published crime statistics organized in a table by the types of crime and district. On a separate page in a pdf was a map that showed the boundaries for each district.
My idea and project was to create a map where you could see where in town particular types of crime happened most.
Based on that idea, my office mate came up with the idea (though not implemented) to find data about bike accidents and map them to streets to see if there were any hotspots that might be particularly dangerous for cycling.
Ideas seem kind of iterative so once I have one idea and expertise in that area, I can’t help but think about other similar problems to solve with my new knowledge.
An example is that because my main job is based around organizing architecture projects and photos, I noticed that during the process of planning my wedding it could be interesting to have a website filled with bouquets organized by the flowers that are in them.
While not a successful business, I learned some new things and ended up implementing concepts to my main business.