This is mentioned elsewhere and the topic itself is marked as solved, but another comment has been added clarify the questions. This is to re-raise the original.

You should be able to post a reply to a topic that you started yourself and mark this reply as the solution to the topic. Many people do this after posting a topic and finding the answer themselves in order to let other people know the solution. Obviously this would need to handled differently for Karma points (and should arguably receive karma points, but maybe this should be handled by giving extra points when the solutions post is voted up by other people (maybe double or triple the normal points, up to a preset limit)

The follow on point is that, you should also be able to undo the act of marking a reply as the solution to a topic. You might (and I haven't done this) mark a reply as the solution without fully testing it and find out later that it has flaws (yes I know you can not mark it at the time and go back to it later, but that's extra steps you have to make and it's easy to forget to get round to it.

Finally, when posting a new topic, maybe the input boxes should be labelled.

Tom