[giantg2]

I would imagine the most interesting problems are the ones that impact you or that you think of, because everyone if different. Sometimes they aren't even "problems" but just improvements or curiosities. You might just need to dig a little more or reflect on things.

For example, I taught myself Java for Android and created an app to calculate party alcohol needs. One part was pretty trivial - cost/volume calculation for the price per pure unit of ethanol. Then I modified the BAC formula so that I could plug in the variables (number of people, estimated average weight, hours partying, etc) and have a slider for how drunk you wanted the people at the party, then it would tell you how much alcohol you needed to buy. I found it very interesting to make. Sadly it never made me rich (or any money for that matter).