Here's one case: the local/popular site to search for used cars sucks. It is slow, hard to see/compare all options, silly reloads the page on each added filter, filled with outdated listings, flooded with ads, and pic slides take forever (all of this on my slow phone over a slow 3g which is how most visitors must be using it). Furthermore, car dealers (who post most listings) complain about service and price. So I built the proverbial mvp and put it in the hands of my marketing partner (you won't sell a line of code if you do not partner with a person/company dedicated to push your stuff) who's already working on a deal with the used car dealers association, pitching a novel business plan, hopefully making some passive income for both of us.