While riddles are fun, I don't think the current format makes for a very good mission. The delay between an answer being given and being confirmed correct/new poster putting up a new riddle really drags out the thread and makes it a crapshoot whether you check the forum during the brief window you can respond (with one or two exceptions the response window has typically been less than half an hour). Also in this day of google I don't think you can actually stump anyone. A better format might have been to just have everyone post their favorite riddle.
Yeah this became obvious pretty quickly after posting this. The better way would have been to post a riddle with your answer in case you got it right. Anyway when we have this coded that won't be a problem because right answers will register without manual acceptance.