Discourse has a new Solved, or Accepted Answer, feature.
When you are viewing a reply to one of your topics, you will see the following checkbox below it:
If the reply answers your question, check the box to mark the topic as solved.
Note, this does not close the topic - other can still reply.
Solved topics are decorated with a checkbox in Category view. This makes it very easy for others to identify what topics might still need attention.
Of couse, not all topics require an accepted answer or even come to a conclusion. But we would love to see topic creators use this feature, as it benefits both those looking for assistance and those searching for previously provided solutions.