Stackoverflow.com has a perfectly good system for accepting an answer to a question. And for questions where you come up with a solution for yourself, writing an answer and marking it as accepted is the correct way forward.
Sadly, many newbies to the site don't seem to understand these concepts, and it's quite common to see questions that have been edited with "SOLVED" or something similar, often with a bit of update text at the end of the question to explain the solution.
At this point, these questions probably need to be closed, but in a lot of cases the existing close options aren't always appropriate.
I therefore propose a new close option: "Question resolved".